Mahui

This work provides a new strategy (by alternating the core) for fine‐tuning the energy levels of nonconjugated zwitterionic molecules and by which a series of stable and one‐step synthesized electron transport layers are obtained for achieving higher performance of polymer solar cells and reducing the cost of industrial manufacture.

Developing stable and cheap organic cathode interlayers (OCIs; to replace metal cathode and expensive OCIs for enhancing the device stability and reducing the manufacturing cost) is an important topic for commercial applications of polymer solar cells (PSCs). Herein, four one‐step synthesized organic electron transport layers (G‐Series electron‐transport layers [ETLs]) with a novel star‐shaped molecular structure consisting of a series of different heteroatom atoms as cores and sulfobetaine ions as a terminal substituent are explored. The energy levels can be finely tuned by applying different heteroatom atoms as cores. With the conventional device structure with poly[[2,6′‐4,8‐di(5‐ethylhexylthienyl)benzo[1,2‐b;3,3‐b]dithiophene][3‐fluoro‐2[(2‐ethylhexyl) carbonyl]thieno[3,4‐b]thiophenediyl]] (PTB7‐Th) as a donor and [6,6]‐phenyl‐C₇₁‐butyric‐acid‐methyl‐ester (PC₇₀BM) as an acceptor, the G‐C2‐based devices exhibit a power conversion efficiency (PCE) of 8.90% with Al as the top electrode, much higher than that of the corresponding Ca/Al‐based device (7.43%). Furthermore, G‐Series‐based solar cells are also more stable than the reference device based on Ca. In addition, these easy‐to‐get ETLs can be widely suitable for other PSCs based on different active layer systems. This work not only shows a new strategy for fine‐tuning energy levels of nonconjugated zwitterionic molecules but also provides simple and stable ETLs for low‐cost and high‐performance PSCs.

Three novel polytriphenylamine‐based polymers (H‐Z1, H‐Z2, and H‐Z3) are designed and applied as hole‐transport layers in all‐inorganic perovskite solar cells. Due to the gradual deepening of the highest occupied molecular orbital energy levels from H‐Z1, H‐Z2 to H‐Z3, the energy loss (E _loss) can be decreased from 0.69, 0.64, to 0.62 eV for H‐Z1, H‐Z2, and H‐Z3, respectively.

The energy loss (E _loss) control via interfacial engineering is a significant indispensible methodology to realize high‐performance all‐inorganic perovskite solar cells (PVSCs). Herein, three novel polytriphenylamine‐based polymer derivatives (H‐Z1, H‐Z2, and H‐Z3) are synthesized, and the energy levels of these polymers are tuned feasibly through introducing the electron‐withdrawing group of trifluoromethyl in the triphenylamine (TPA) unit. These very deep HOMO energy levels are very beneficial for improving the open‐circuit voltages (V_ocs) in PVSCs with the potentially decreased E _losss. Due to the gradual deepening of HOMO energy levels from H‐Z1, H‐Z2 to H‐Z3, the V_ocs are elevated from 1.23, 1.28 to 1.30 V, respectively, where the E _loss s are decreased from 0.69, 0.64, to 0.62 eV for H‐Z1, H‐Z2, and H‐Z3, respectively. Interestingly, both of the H‐Z1‐ and H‐Z2‐based devices show the highest PCEs, over 14%, in all‐inorganic PVSCs, which are effectively comparable to the results of reference device using Spiro‐OMeTAD as HTL. Thus, through the efficient atomic engineering and chemical modification in corresponding p‐typed polymers, excellent hole transport polymers are achieved for high‐performance and stable PVSCs with very low E _loss.

A new small molecule (SM)‐acceptor, POIT‐IC4F, is developed. Due to the synergistic effects of side‐chain engineering and fluorination on the SM‐acceptor to simultaneously broaden spectral response and minimize voltage loss, the annealing‐free organic solar cells achieve a high device efficiency of 13.8%.

Herein, three small molecule (SM)‐acceptors (POIT‐IC, POIT‐IC2F, and POIT‐IC4F) are developed by combining the side‐chain engineering located on the sp³‐hybridized carbon atoms of the fused‐ring core and the fluorination of end groups. From ITIC to POIT‐IC, POIT‐IC2F, and then to POIT‐IC4F, the SM‐acceptors show gradually broadened absorption spectra, increased maximum extinction coefficient, crystallinity, and electron mobilities due to the synergistic effects of side‐chain engineering and fluorination. Compared with nonfluorinated ITIC and POIT‐IC, as fluorination broadens the molecular spectra, POIT‐IC2F and POIT‐IC4F with alkoxyphenyl side chains show less decreased LUMO levels than IT‐IC2F and IT‐IC4F with alkylphenyl side chains, which are conducive to both higher V _oc and J _sc for organic solar cells (OSCs). Combined with polymer donor PM6, the POIT‐IC4F‐based OSCs achieve a device efficiency of up to 13.8% with a high V _oc of 0.91 V and J _sc of 20.9 mA cm⁻², which are significantly higher than that of the control OSCs based on ITIC (8.9%), POIT‐IC (10.1%), or IT‐IC4F (12.2%). An efficiency of 13.8% is one of the highest PCEs reported for the annealing‐free OSCs. Our results show that the synergistic effects of side‐chain engineering and fluorination on SM‐acceptor can simultaneously broaden spectral response and minimize voltage loss of OSCs and ultimately achieve high device efficiency.

Perovskite solar cell technology is in the advent of commercial entrance. These materials offer several new value propositions that can allow short‐term monetization in emerging applications, such as Internet‐of‐things or building‐integrated photovoltaics. Prospective offerings perovskite photovoltaics could deliver for high‐value markets, such as utility‐scale photovoltaics, and the feasibility of large deployments are also discussed.

Perovskite solar cell technology is fast approaching its first commercial deployment, with the 10‐year mark since the first research having passed recently. Commercial entrance seems very tangible, but there are a number of remaining challenges related to various economic and technical factors. Conventional photovoltaic markets, such as utility scale photovoltaics, are quite rigid and very demanding for a new entrant. Perovskites offer several new value propositions, which offer monetization prospects in the near future, if properly used. In particular, functionalities such as flexibility, high specific power, and good low‐light performance enable new applications and broadening of the conventional PV usage. The specific cases of internet of things and building‐integrated photovoltaics are discussed, and market opportunities are analyzed. Technology incubation with simultaneous market presence in emerging applications can provide essential economic stability and time for the technology to develop into its full potential. Opportunities in high‐value markets and massive‐scale deployment are also addressed, with the analysis of potentially disruptive offerings being promised by perovskite photovoltaic technology.

Interface engineering is widely recognized as an effective strategy to improve the efficiency and stability of perovskite solar cells. This review is intended to provide a deep understanding of interface design principles for highly efficient and stable perovskite photovoltaic devices and a timely overview for state‐of‐the‐art interfacial materials in this rapidly developing field.

Exceptionally high efficiencies for organic–inorganic hybrid perovskite solar cells (PSCs) have been achieved. However, their operational stability still needs to be improved. The intrinsic instability of halide perovskites caused by the presence of volatile organic cations, as well as the degradation of hybrid perovskites induced by the adverse permeation of environmental water (H₂O)/oxygen (O₂) and the undesired ion diffusion or migration are the major reasons. Beyond strengthening perovskites themselves, interface engineering is now regarded as a valid strategy to prolong device lifetime by preventing the undesired degradation pathways. This comprehensive review highlights the utilization of practical interface engineering for enhancing the efficiency and stability of organic–inorganic lead halide PSCs. First, the impacts of interface design on the energy‐level alignment and carrier dynamics are overviewed. Second, recent progresses on the development of interfacial materials for simultaneously achieving high efficiency and stability of PSCs are summarized. At last, the interfacial layer design principles along with future outlook of this rapidly developing field are discussed.

The initial stages of MAPbI₃ photodegradation prior to any significant change in light absorption are studied, with independent control of sample temperature and sunlight intensity (1–500 suns). Under the combined action of light and heat, a strong reduction of photoluminescence (PL) is observed. In contrast, illumination of perovskite films (with an intensity up to 500 suns) without heating induces considerable PL enhancement.

The initial stages of photo‐degradation of CH₃NH₃PbI₃ (MAPbI₃) thin films prior to any significant change in light absorption are studied in experiments with independent control of sample temperature and intensity of concentrated sunlight from 50 to 500 suns. Photo‐stability of the MAPbI₃ film is revealed to be extremely sensitive to the sample temperature. Under the combined action of light and heat (either by concentrated sunlight or by external heating), a strong reduction of the film photoluminescence (PL) without changes in the perovskite light absorption can be observed during the initial stages of degradation. In contrast, illumination of perovskite films (with intensity up to 500 suns) without heating (using chopped concentrated sunlight) induces considerable PL enhancement while the optical absorption spectrum remains unchanged. With accurate temperature control, aging under concentrated sunlight results in similar instability trends as that under 1 sun.

The power conversion efficiency of the carbon‐based perovskite solar cells is enhanced by 21.4% simply by interfacial post‐treatment with cesium acetate. The nonencapsulated device can remain stable for 4 months without observable degradation. The improved performance is attributed to the better matched energy levels and the reduced defect density.

The interface between the perovskite layer and carbon electrode is important for printable carbon‐based perovskite solar cells (PSCs) to improve the power conversion efficiency (PCE) and device stability. A series of acetate salts are employed to in situ post‐modify the interface between the perovskite layer and carbon electrode for printable carbon‐based PSCs by the post‐treatment method. Cesium acetate (CsAc) is identified to enhance the average PCE from 12.6% to 15.3%. The stabilized output PCE reaches 15.6%, and the highest open‐circuit voltage (V _OC) is 1.1 V, representing a new milestone in increasing the ratio of V _OC/E _g (E _g: bandgap of perovskite) to be 0.67 for the printable carbon‐based PSCs without hole transporting materials. Moreover, the device stability in air is also improved by CsAc post‐modification. The improved performance is attributed to the better matching of energy levels of the perovskite layer with a carbon electrode and reduced defect density in the perovskite layer via in situ produced methylammonium acetate and ion replacement. This simple and effective CsAc post‐treatment method opens a new promising direction for developing scalable carbon‐based PSCs.

The linking topology effect and the doping effect on the optical and electronic properties of a series of carbazole‐based hole‐transport materials (HTMs) with 2,7‐substitution and 3,6‐substitution are systematically investigated. The results clearly demonstrate that the 2,7‐substituted carbazole‐based HTMs display higher hole mobility and conductivity, thereby exhibiting better device performance in both solid‐state dye‐sensitized solar cells and perovskite solar cells.

Carbazole is a promising core for the molecular design of hole‐transport materials (HTMs) for solid‐state mesoscopic solar cells (ssMSCs), such as solid‐state dye‐sensitized solar cells (ssDSSCs) and perovskite solar cells (PSCs) due to its low cost and excellent optoelectronic properties of its derivatives. Although carbazole‐based HTMs are intensely investigated in ssMSCs and promising device performance is demonstrated, the fundamental understanding of the impact of linking topology on the properties of carbazole‐based HTMs is lacking. Herein, the effect of the linking topology on the optical and electronic properties of a series of carbazole‐based HTMs with 2,7‐substitution and 3,6‐substitution is systematically investigated. The results demonstrate that the 2,7‐substituted carbazole‐based HTMs display higher hole mobility and conductivity among this series of analogous molecules, thereby exhibiting better device performance. In addition, the conductivity of the HTMs is improved after light treatment, which explains the commonly observed light‐soaking phenomenon of ssMSCs in general. All these carbazole‐based HTMs are successfully applied in ssMSCs and one of the HTMs X50‐based devices yield a promising efficiency of 6.8% and 19.2% in ssDSSCs and PSCs, respectively. This study provides guidance for the molecular design of effective carbazole‐based HTMs for high‐performance ssMSCs and related electronic devices.

A hole‐transporting material (HTM), termed V1160, based on four TPD‐type fragments connected by a Tröger's base structural core, is synthesized, characterized, and applied as an HTM in perovskite solar cells. Demonstrating an over 18% power conversion efficiency, the fully amorphous nature of V1160, suggesting further studies in TPD‐based materials, is warranted.

One of the obstacles to the commercialization of perovskite solar cells (PSCs) is the high price and morphological instability of the most common hole‐transporting material (HTM) Spiro‐OMeTAD. Herein, a novel HTM, termed V1160, based on four N,N′‐bis(3‐methylphenyl)‐N,N′‐diphenylbenzidine (TPD)‐type fragments, fused by a Tröger's base core, is synthesized and successfully applied in PSCs. Investigation of the optical, thermal, and photoelectrical properties shows that V1160 is a suitable candidate for application as an HTM in PSCs. A promising power conversion efficiency (PCE) of over 18% is demonstrated, which is only slightly lower than that of Spiro‐OMeTAD. Moreover, V1160‐based devices exhibit improved performances in dopant‐free configurations and superior stability. Favorable morphological properties in combination with a simple synthesis make V1160 and related materials promising for HTM applications.

An amorphous passivation layer using phenethylammonium iodide for amply covering the surface and grain boundaries of the CH₃NH₃PbI₃ film, results in the reduction of trap density and suppression of nonradiative recombination.

Organic–inorganic lead halide perovskite solar cells have realized a rapid increase of power conversion efficiency (PCE) in the past few years. However, their performance still suffers trap‐assisted decline due to defects at the surface and grain boundaries of the perovskite film. Herein, a phenethylammonium iodide‐lead iodide (PEAI‐PbI₂) passivation layer is formed on the CH₃NH₃PbI₃ perovskite film. The characterization results indicate that the PEAI covering layer leads to the reduction of surface defects and suppression of nonradiative recombination. By manipulating this surface passivation method, a remarkably improved V _OC of 1.16 V and an enhanced PCE of 20.8% are achieved.

An aggregation‐induced emission (AIE) molecule is successfully employed as an effective hole transport material in an inverted planar perovskite solar cell. The improvement of perovskite crystallinity and the suppression of nonradiative recombination at the AIE/perovskite interface result in enhanced device performance and stability as compared with the poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS)‐based control one.

Organic hole‐transport materials (HTMs) are very promising for perovskite solar cells (PSCs) because the molecule structure is engineered via facile chemical routes. Herein, an aggregation‐induced emission (AIE) molecule, 2‐(2,7‐bis(4‐(bis(4‐methoxyphenyl)amino)phenyl)‐9H‐fluoren‐9‐ylidene)malononitrile (TFM), is successfully employed for the first time as a HTM in an inverted planar PSC, obtaining a promising device performance superior to that of the control device with poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) HTM. An optimal power conversion efficiency (PCE) of 16.03% is obtained for the TFM‐based PSCs with a J _sc of 22.68 mA cm⁻², V _oc of 0.97 V and FF of 72.9%, while that of the control PEDOT:PSS‐based device is 14.95%. Steady‐state and time‐resolved photoluminescence results reveal suppressed nonradiative recombination at the TFM/perovskite interface that is attributed to the effective passivation of the uncoordinated Pb at the perovskite surface by the CN⁻ groups of TFM molecules, as confirmed by X‐ray photoelectronic spectroscopy measurements. In addition to the passivation, the hydrophobic character of TFM films also contributes to the improved device stability. The findings demonstrate the potential of AIE molecules in PSCs and also paves a novel way to improve device performance and stability by molecular structure engineering of AIE molecules in the future.

A simple dynamic antisolvent quenching process is used for the efficient and reliable fabrications of uniform and high‐quality 10 × 10 cm² large‐area perovskite films. The perovskite module fabricated using this technique achieves an efficiency approaching 18% and a certified efficiency of 17.4% with the aperture area of 53.64 cm².

Perovskite solar cells represent a promising photovoltaic technology, which achieves record power conversion efficiencies over 24%. However, a problem on the commercial processing is the unavoidable efficiency loss during the scalable fabrication of perovskite solar module. The efficient and reliable fabrications of high‐quality large‐area perovskite films guarantee commercialized up‐scaling of perovskite solar cells with high efficiency. Herein, a simple dynamic antisolvent quenching (DAS) process is presented to understand large‐area uniform perovskite films to obtain an efficient perovskite solar module. This method provides a facile and universal approach to fabricate cracks‐free and uniform large‐area mixed‐cation perovskite films. A champion module device (10 × 10 cm²) with efficiency of 17.82% (another module with certified efficiency of 17.4%) is obtained using DAS process.

Annealing a poly(ethylene oxide) film over its glass transition temperature leads to the formation of a cross‐linking complex with metal ions at the tin oxide quantum dot and perovskite interface, which passivates the interface defects for enhanced electron transfer from the perovskite layer to cathode.

Interface engineering is critical for achieving high‐efficiency and high‐stability perovskite solar cells (PSCs). Herein, a new interface engineering approach—poly(ethylene oxide) (PEO) modification of SnO₂ quantum dot (QD) film—to improve electron transport is introduced. It is found that when the PEO film is annealed over its glass‐transition temperature, the ether‐oxygen unshared electron pair in the PEO film activates to form a crosslinking complex with metal ions at the SnO₂ QD and perovskite interface, which triggers heterogeneous nucleation over the perovskite precursor film and is beneficial for achieving uniform and dense perovskite films. PEO is also shown to passivate the bulk defects of perovskite films and the interface defects between SnO₂ QD and perovskite, which promotes electron‐transferring from the perovskite layer to cathode. PSCs based on SnO₂ QD with PEO treatment exhibit an enhanced efficiency, leading to a champion PCE of 20.23%, with good reproducibility and stability.

The oxygen‐stabilizing effect of [6,6]‐phenyl‐11 C₆₁‐butyric acid‐(3,4,5‐tris(2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)phenyl)methanol ester (PCBB‐OEG) is investigated and it is found that the excellent electron transfer/extraction of PCBB‐OEG can reduce the generation of superoxides and enhance the stability of perovskite solar cells (pero‐SCs). The resulting pero‐0.1/[6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PCBM):PCBB‐OEG‐based pero‐SC delivers a high power conversion efficiency of 20.49% as well as high long‐term stability under ambient atmosphere at ≈50% humidity.

Poor stability is one of the main limiting factors for the commercialization of perovskite solar cells (pero‐SCs). The degradation of perovskite films is usually triggered by the reaction of the perovskite active layer with the superoxide when exposed in ambient atmosphere, which is not prevented by simple encapsulation. Herein, an oxygen‐stabilizing effect is found by utilizing a hydrophilic [6,6]‐phenyl‐C₆₁‐butyric acid‐(3,4,5‐tris(2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)phenyl)methanol ester (PCBB‐OEG) as a dopant of the perovskite film and electron‐transporting layer (ETL). PCBB‐OEG accelerates photoelectron transport in perovskite films and enhances the electron‐extracting ability of ETL. This process is demonstrated to efficiently prevent the reaction between electrons and oxygen to form a superoxide. Hence, the presence of PCBB‐OEG in the perovskite film improves its stability against oxygen. The stability and efficiency of pero‐SCs are further improved by doping PCBB‐OEG in [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) ETL. As a result, the p‐i‐n pero‐SCs with PCBB‐OEG as an additive in both the perovskite active layer and ETL show the best power conversion efficiency of 20.49%. Importantly, the related device retains 98% of this initial efficiency after 60 days of storage in ambient atmosphere without encapsulation.

In this review, multifunctional molecules for perovskite solar cells (PSCs) are introduced. All the molecules can help to improve the performance of PSCs, such as forming low‐dimensional or dimensionally mixed perovskites and passivating defects, thus inducing good crystal growth behavior, improving the morphology of perovskite films, and facilitating charge transport. Eventually, PSCs with superior photoelectric properties and better stability can be obtained.

Organic–inorganic halide perovskite solar cells (PSCs) have recently attracted much attention with the recent certified power conversion efficiency (PCE) record exceeding 24%. To date, many approaches have been developed for producing high‐performance PSCs, in which the application of multifunctional molecules plays an important role. The multifunctional molecules can modify the morphology of perovskite films and/or passivate the surface defects through interactions with the perovskites' boundaries and/or the charge carrier extraction interfaces. As a result, both the PCEs and the stability of PSCs are improved. The recent progress in the development of multifunctional molecules‐incorporated PSCs is reviewed. The importance of further understanding of the role of the multifunctional molecules in the perovskite film formation process and defect passivation mechanism is discussed. Further research in terms of multifunctional molecules can help to develop high‐performance devices with long‐term stability for future practical applications of PSCs.

Three novel low‐bandgap fused‐ring electron acceptors, BPIC, BPIC‐2Cl, and BPIC‐4Cl are designed based on a heptacyclic core, using phenyl‐substituted benzo[1,2‐b:4,5‐b′]dithiophene as the central unit, end‐capped with 1,1‐dicyano methylene‐3‐indanone (INCN), mono‐chlorinated INCN, and di‐chlorinated INCN moieties, respectively. The effects of chlorination on optical and electronic properties of molecules, film morphology, and photovoltaic device performance are investigated.

A new heptacyclic core based on phenyl‐substituted benzo[1,2‐b:4,5‐b']dithiophene (BDT) is designed and paired with 1,1‐dicyano methylene‐3‐indanone (INCN) end group to construct a nonfullerene acceptor, BPIC. The strong aggregation and large phase separation in the poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))]) (PBDB‐T):BPIC blend cause inefficient exciton dissociation and ineffective charge transport, resulting in a low 11.12% power conversion efficiency (PCE) with low short‐circuit current density (J _SC) and fill factor (FF). To finely control the active‐layer nanomorphology, the chlorine atom is introduced into the INCN termini, and di‐chlorinated BPIC‐2Cl and tetra‐chlorinated BPIC‐4Cl are synthesized. It is an interesting phenomenon that, unlike other literature reports, while the di‐chlorination reduces crystallinity and phase‐separation scale, further chlorination increases crystallinity and phase separation. The PBDB‐T:BPIC‐2Cl device exhibits suitable molecular packing and nearly ideal nanoscale phase separation, which facilitates exciton dissociation and charge transport and thus yields the higher PCE of 12.63% with significantly improved J _SC and FF. PBDB‐T:BPIC‐4Cl device, however, exhibits strong stacking intensity and excessively large phase separation, leading to the clearly reduced J _SC, FF, and PCE of only 8.23%. This work demonstrates that novel phenyl‐substituted BDT core and delicated chlorination strategy provides powerful tools for high‐performance nonfullerene acceptors in organic solar cells.

In recent years, tremendous research interest is devoted on organic–inorganic halide perovskites because of their excellent optical and electrical properties, which make them intriguing photovoltaic materials. The record efficiency of Pb‐based halide perovskite solar cells (PSCs) has beyond 24%, fulfilling their potential toward industrialization. The photovoltaic performance of PSCs is predominantly determined by the quality of the perovskite film, which in turn, is controlled by the fabrication process. Therefore, a comprehensive and in‐depth understanding of fundamental polycrystalline perovskite film formation is imperative for further development of PSCs manufacturing. This review summarizes recent advances in the field of PSCs and mainly reviews the fundamental knowledge of nucleation and growth during perovskite crystallization from solution processing methods, promising small area and largescale solution manufacturing methods combined with their properties and relevant PSCs' performance, then a brief overview of stabilization strategies and cost discussions are presented. At the end of the review, we consider the challenges and outlooks of PSCs' development for up‐and‐coming photovoltaic technology for industrial application.

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A simple coalloying strategy is applied to partly substitute HC(NH₂)₂/CH₃NH₃ (FA/MA) and I⁻ in FA_0.85MA_0.15PbI₃ perovskite by Cs⁺ and Ac⁻ respectively, which is an effective way to improve the tolerance factor, crystallinity, electronic properties, and band structure of FA_0.85MA_0.15PbI₃ materials. Consequently, the coalloyed perovskite solar cells yield a champion power conversion efficiency of 21.95% with negligible hysteresis and high stability.

A simple coalloying strategy is applied to improve the efficiency and stability of FA_0.85MA_0.15PbI₃ perovskite solar cells (PSCs) by using cesium acetate (CsAc) as an additive. It is found that the simultaneous incorporation of cation (Cs⁺) and anion (Ac⁻) into the FA_0.85MA_0.15PbI₃ film is an effective approach to realize lattice contraction, grain size enlargement, photoelectric properties improvement, band structure modulation, and therefore the optimization of the efficiency and stability of PSCs. At optimal CsAc alloying, the FA_0.85MA_0.15PbI₃ PSCs achieve a maximum power conversion efficiency (PCE) of 21.95% and an average of over 21%. In addition, the alloyed PSCs retain 97% of their initial PCE values after aging for 55 days in air without encapsulation.

The bistricyclic aromatic enes molecules with multiple conformations are selected to further explore the effect of conformation on performance systematically. Then, a machine learning model is used to screen the more matched donor and predict the energy conversion efficiency of the device. A route from microscopic conformation to macroscopic performance design and characterization for organic photovoltaic device is established.

Theoretical predictions of macroscopic performance (power conversion efficiencies [PCEs]) and experimental analyses for microscopic material (conformation) have always urged for organic photovoltaics. A series of acceptors based on multi‐conformation bistricyclic aromatic enes core have been designed. The results suggested that A4‐2, A5‐2, and T4‐2 show the full folded conformation, fitting, and exhibiting advantageous properties of various parts for acceptors effectively, thus getting high V _OC and J _SC (k _CS/k _CR exceeds 10¹²) as well. Their PCEs of devices matching different donors were predicted through machine learning (ML). In traditional device structures and crude environments, a maximum PCE is about seven times higher than original. Herein, a comprehensive investigation, ranging for conformations → donor/acceptor interfaces → morphology → PCEs, is carried out by pure theoretical methods. Therefore, this quantitative micro‐analysis combined with the ML intelligent prediction leads to a new approach in the development of the next generation of nonfullerene acceptors.

This review aims at presenting a comprehensive overview of the latest progress on perovskite solar cells (PSCs), especially the strategies toward enhancing their near‐infrared light harvesting. An in‐depth understanding of the working mechanism of tandem solar cells (TSCs) and integrated perovskite/organic solar cells (IPOSCs) is presented, and the recent developments of perovskite/Si, perovskite/Cu(In_1–x , Ga _x )Se₂ TSCs, and IPOSCs are further highlighted.

The emerging perovskite materials present great opportunities for cost‐saving and efficient photovoltaic devices. However, perovskite solar cells (PSCs) suffer from the limitation of short optical absorption edge, resulting in most of the near‐infrared (NIR) light being wasted. Recently, strategies toward broadening the NIR spectra response and further improve the power conversion efficiency of PSCs have attracted extensive attention. In this review, the unique features of perovskite materials are first introduced; subsequently, the current developments of organic–inorganic hybrid PSCs and all‐inorganic PSCs are highlighted. Then, a detailed summary of the strategies toward enhancing the NIR light harvesting of PSCs, namely, perovskite/Si and perovskite/Cu(In_1–x , Ga _x )Se₂ tandem solar cells (TSCs) and the integrated perovskite/organic solar cells (IPOSCs), is presented. After an in‐depth understanding of the working mechanism of TSCs and IPOSCs, a comprehensive overview about their recent developments, key detrimental factors restricting their further performance enhancement, and feasible countermeasures to conquer these scientific and technological problems are given. In the end, the perspectives on the related materials and devices are addressed.

In perovskite solar cells (PSCs), hybrid perovskite:fullerene phases have been proposed to suppress macroscopic current hysteresis behavior by alleviating ion migration. However, the understanding of how fullerenes exactly alleviate the current hysteresis and what is the influence of fullerenes in such hybrid phases are still unclear from a microscopic viewpoint. Here, the intentional incorporation of fullerene into perovskite has been employed to examine how fullerene exactly reduce the macroscopic current hysteresis. The location and distribution of fullerenes in the hybrid phase were confirmedly visualized by conductive atomic force microscopy and Kelvin probe force microscopy measurements. Fullerenes located at grain boundaries function as the beneficial effect on choking the channels of ion migration and also as the electron traps that compromise the photocarrier extraction. Macroscopic current hysteresis originating from the influxes of all nanoscopic grain boundary current signals is avoided in PSCs based on the hybrid perovskite:fullerene phases. Our results not only provide the strong correlation between nanoscopic and macroscopic current hysteresis behaviors, but also clearly clarify the role of fullerene how to reduce the current hysteresis in hybrid phases and thus prototype devices.

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Ternary polymer solar cells (PSCs) are fabricated with PBDB‐T:PC₇₁BM:INPIC‐Si as the active layers. The power conversion efficiency (PCE) reaches 13.26% for ternary PSCs with 20 wt% PC₇₁BM, which is larger than that for INPIC‐Si or PC₇₁BM‐based PSCs with PCEs of 11.79% or 6.26%. Light absorption, exciton distribution, and film morphology can be simultaneously optimized by incorporating appropriate PC₇₁BM.

Ternary polymer solar cells (PSCs) are designed by incorporating varied PC₇₁BM into a PBDB‐T:INPIC‐Si‐based binary system. The PC₇₁BM incorporation can replenish weak absorption of PBDB‐T and INPIC‐Si in the short wavelength from 300 to 500 nm. Effective charge transport channels can be formed in ternary active layers due to good compatibility of the used materials. The optimized ternary PSCs exhibit a power conversion efficiency (PCE) of 13.26% with short‐circuit current density (J _SC) of 20.98 mA cm⁻², open‐circuit voltage of 0.892 V, and fill factor (FF) of 70.84%. The 13.26% PCE is among the top values for ternary PSCs with fullerene derivative and nonfullerene materials as acceptors. An approximately 12.5% PCE improvement is obtained compared with INPIC‐Si‐based binary PSCs, originating from simultaneously increased J _SC and FF of the optimized ternary PSCs. The balanced photon harvesting is obtained in the whole wavelength range by regulating PC₇₁BM content in acceptors, leading to increased J _SC of ternary PSCs. The molecular arrangement and phase separation are well optimized in ternary blend films, resulting in the enhanced FF of ternary PSCs. The photogenerated exciton distribution is optimized according to optical field distribution of ternary active layers, which further support the J _SC and FF improvement.

Perovskite solar cells (PSCs) have recently attracted tremendous interest due to their feasibility, high power conversion efficiency (PCE), light weight and flexible architecture. However, there still presents some challenges for cheap mass fabrication in commercial application. In this work, we employed an efficient Zn‐SnO_x electron transport layers (ETLs) by low temperature (100 °C) electron beam (E‐beam) method. Doping Zn²⁺ in SnO₂ could improve the conductivity, suppress charge recombination and optimize the energy level structure of SnO₂, leading to an improved PCE from 18.95% to 20.16%. More importantly, the PCE of modified device could remain more than 80% of its initial values for 800 h in the ambient air with a relative humidity of ≈40%. The flexible device could exhibit a PCE of 15.25% and remain an initial PCE of 83% after 100 bending cycles. The efficient and flexible PSCs could be potentially used as a wearable energy power source. Low temperature preparation of ETL and the excellent performance of device present a great commercial potential for future application.

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Planar perovskite solar cells (PSCs) are promising photovoltaic devices accompanied with the obvious advantages of easy fabrication and scalability. Herein, a method toward obtaining high‐quality FA_1–x MA _x PbI₃ film‐based planar PSCs by sequential deposition of chlorobenzene and methylammonium chloride is proposed. A champion power conversion efficiency (PCE) of 18.57% is achieved and 91% of the initial PCE is maintained after 500 h.

Planar perovskite solar cells (PSCs) are promising photovoltaic devices accompanied with the obvious advantages of easy fabrication and scalability. To achieve highly efficient and stable PSCs, the morphology control of perovskite crystallization is crucial. Herein, a novel method toward obtaining high‐quality FA_1–x MA _x PbI₃ films by spin coating methylammonium chloride (MACl) and chlorobenzene (CB) in different sequential processes on the top of substrates is proposed. Controlling the nucleation process is beneficial for the formation of a homogeneous nucleus at the nucleation stage, leading to highly ordered seed crystals and an ultrasmooth perovskite film. As determined by photoluminescence and time‐resolved photoluminescence spectroscopy, the defects and the associated charge recombination are notably reduced by the high crystalline quality of perovskite film. Finally, a champion power conversion efficiency (PCE) of 18.57% is achieved and 91% of the initial PCE is retained after 500 h. The devices are stored in an ambient condition with 20% relative humidity (RH) at 30 °C in the dark.

A facile method is reported for preparing α‐CsPbI₃ perovskite films at room temperature by introducing ascorbic acid (AA) in the CsPbI₃ precursor solution. The champion device not only showed a high efficiency of 11.44% but also had excellent stability, retaining more than 76% of its initial efficiency after aging in ambient conditions for 250 h without encapsulation.

The all‐inorganic α‐CsPbI₃ perovskite with superb thermal stability and suitable band gap for light harvesting has been considered as a promising candidate for efficient perovskite solar cells (PSCs). However, the photoactive black α‐CsPbI₃ is thermodynamically unstable and transforms spontaneously into nonphotoactive yellow δ‐phase at room temperature. Herein, a facile method is reported to prepare α‐CsPbI₃ perovskite films with high stability at room temperature by mixing a small amount of ascorbic acid (AA) in the CsPbI₃ precursor solutions. It is revealed that the interaction of AA with the CsPbI₃ precursors could effectively inhibit the rapid crystallization of CsPbI₃ and reduce the size of the coordination colloidal, and thus decrease the grain size of CsPbI₃ for preparing long‐term stable α‐CsPbI₃ films. The PSCs based on the AA‐stabilized CsPbI₃ films exhibit reproducible photovoltaic performance with a champion efficiency of up to 11.44% and stable output of 11.30%, along with excellent stability, retaining more than 76% of its initial efficiency after aging in ambient conditions for 250 h without encapsulation. Most importantly, such low‐cost, solution‐processable inorganic PSCs with high performance also show promising potential for large‐scale preparation.

The large grains and high crystallinity of Pb(Ac)₂‐doped α‐CsPbI₂Br active layers with CsBr passivation is realized by a two‐step annealing process. The corresponding planar all‐inorganic CsPbI₂Br perovskite solar cells exhibit a long‐term ultrahigh power conversion efficiency of 16.37%, with a substantially improved V _OC of 1.271 V.

All‐inorganic CsPbI₂Br perovskite has attracted increasing attention, owing to its outstanding thermal stability and suitable bandgap for optoelectronic devices. However, the substandard power conversion efficiency (PCE) and large energy loss (E _loss) of CsPbI₂Br perovskite solar cells (PSCs) caused by the low quality and high trap density of perovskite films still limit the application of devices. Herein, the post‐treatment of evaporating cesium bromide (CsBr) is utilized on top of the perovskite surface to passivate the CsPbI₂Br–hole‐transporting layer interface and reduce E _loss. The results of microzone photoluminescence indicate that the evaporated CsBr gathered at the grain boundaries of CsPbI₂Br layers and Br‐enriched perovskites (CsPbI _x Br_3−x , x < 2) are formed, which can provide protection for CsPbI₂Br. Therefore, the gaps between crystal grains are filled up, and the recombination loss of the all‐inorganic CsPbI₂Br PSCs is reduced accordingly. The champion device exhibits high open‐circuit voltage and a PCE of 1.271 V and 16.37%, respectively. This is the highest reported PCE among all‐inorganic CsPbI₂Br PSCs reported so far. In addition, the stability of CsPbI₂Br PSCs is effectively improved by CsBr passivation, and the device without encapsulation can retain 86% of its initial PCE after 1368 h of storage, which is beneficial for practical applications.

Here, studies on regulation of the interfacial charge balance in SnO₂‐based planar perovskite solar cells are reported. SnO₂ with optimum thickness exhibits enhanced charge balance. Moreover, trap‐assisted carrier recombination is significantly suppressed by using diethylenetriaminepentaacetic acid as a passivator. As a result, the champion device demonstrates a promising efficiency of 21.28% with negligible hysteresis and much improved environmental stability.

Control of dynamics at the electron transport layer–perovskite interface, such as charge transfer and recombination, is essential in achieving high‐efficiency planar perovskite solar cells (PSCs). Herein, it was observed that the trade‐off between unfavorable electron transport of a thick SnO₂ film and serious electron recombination at thin SnO₂ film/perovskite interfaces is essential for the performance of SnO₂‐based planar PSCs. The optimized efficiency of devices beyond 20% is obtained by using a two‐step deposition of SnO₂. Moreover, trap‐assisted carrier recombination is significantly suppressed by using the diethylenetriaminepentaacetic acid passivator via the formation of coordination with undercoordinated Sn and Pb²⁺ ions. As a result, the champion device demonstrates a promising efficiency of 21.28% with negligible hysteresis and much improved environmental stability, i.e., retaining 98% of the initial efficiency under ambient atmosphere over 1000 h.

Bi₂Te₃ nanoplates with a tunable energy structure are introduced in inorganic perovskite solar cells (PSCs), accelerating hole transport by the matched band alignment. Confirmed by systematic measurements, charge recombination is largely suppressed due to lower trap density and higher carrier mobility. The optimal PSC with Bi₂Te₃ exhibits highly decreased V _OC loss and enhanced long‐term stability over 50 days.

To solve the thermal instability issue of organic–inorganic hybrid perovskites, all‐inorganic perovskite solar cells (PSCs) have been featured in the spotlight. However, their power conversion efficiencies (PCEs) are far from satisfactory due to the substantially radiative and nonradiative recombination of charge carriers in the common‐structured devices. Herein, bismuth telluride (Bi₂Te₃) nanoplates are designed as an interlayer between cesium lead halide (CsPbBrI₂) and 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,90‐spirobifluorene (Spiro‐OMeTAD) to reduce the notorious trap states and charge recombination. Confirmed by systematic electrochemical and photoelectrical techniques, the Bi₂Te₃ interlayer optimizes hole extraction and transport efficiency because of the matched band level structure and drastically reduces trap defect densities. Prolonged effective lifetime and shorter diffusion time induced by the Bi₂Te₃ interlayer reveal less electron–hole recombination and more efficient carrier transport, which lead to a larger photocurrent and less open circuit voltage loss of PSCs. The all‐inorganic PSCs with the optimal Bi₂Te₃ interlayer exhibit a highly enhanced PCE of 11.96%. Moreover, Bi₂Te₃ also acts as a blocking layer for the migration of iodide ions, silver, and moisture, resulting in a considerable device stability of more than 70% of initial PCE after 50 days without extra encapsulation. This low‐cost and facile method for efficient and stable all‐inorganic PSCs offers great promise as a next‐generation renewable energy source.

A two‐step spin‐coating procedure is used to fabricate a chlorophyll derivative (CHL) and [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM)‐based “bilayer” (BL) organic solar cells in comparison with the bulk heterojunction (BHJ) devices. The BL devices yield a high efficiency, over 5%, which is much higher than that of the BHJ devices due to better CHL aggregate phase retention.

The power conversion efficiency (PCE) of chlorophyll (Chl)‐based organic solar cells (OSCs) is generally about 2%. Herein, a Chl‐a derivative (CHL) and [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM) are successfully used to fabricate Chl‐based OSCs with PCE over 5%. Two different preparation methods are used to prepare the active layer: 1) two‐step spin‐coating the self‐aggregated CHL and PC₇₁BM solutions sequentially and 2) one‐step spin‐coating the solution of CHL:PC₇₁BM blends, forming the “bilayer” (BL) and traditional bulk heterojunction (BHJ) configurations, respectively. Based on the aforementioned two kinds of active‐layer preparation methods, both inverted and regular types of OSCs are successfully investigated. All four types of devices work normally, which is likely due to the ambipolar characteristics of the CHL aggregate. Unexpectedly, the BL‐based devices yield PCEs of 5.17% for the regular type and 5.19% for the inverted type, which are higher than those of the BHJ‐based devices (3.96% for the regular type and 3.50% for the inverted type). The main improvement in PCEs of BL‐based devices comes from the enhanced short‐circuit currents, which is due to the decreased charge transfer resistance and enlarged photocurrent contribution of PC₇₁BM as well as slightly enhanced electron and hole mobilities.

Sn‐based perovskite solar cells (PSCs) with 6.33% power conversion efficiency are fabricated with an aperture area of 1 cm² by introducing a post‐deposition vapor annealing method. The fabricated Sn‐based PSCs show promising stability, both under dark and maximum power‐point tracking conditions.

Sn‐based perovskite solar cells (PSCs) are promising alternatives to replacing toxic Pb‐based PSCs, which have shown a rapid rise in photovoltaic applications in the past 1 year. However, the reported Sn‐based PSCs are often fabricated with a small aperture area (typically 0.02–0.1 cm²) because forming homogeneous pinhole‐free continuous films over a large surface area is still challenging. Herein, a post‐deposition vapor annealing (PDVA) process assisted by methylammonium chloride vapor is presented that enables the fabrication of stable, homogeneous pinhole‐free FASnI₃ perovskite absorber films with low crystal defects and low surface recombination over a relatively large area up to 1.02 cm². Inverted planar solar cells fabricated with a 1.02 cm² aperture area show a maximum power conversion efficiency of 6.33% with high reproducibility and stability. The shelf‐lifetime stability test shows that the PSCs retain 90% of their performance for more than 1000 h when stored in a N₂‐filled glove box and under dark conditions. The preliminary light‐soaking stability tests under continuous illumination and maximum power‐tracking conditions are relatively promising. This study marks an important step toward the up scaling of Sn‐based PSCs.