Chen Weijie

Publication date: August 2019

Source: Nano Energy, Volume 62

Author(s): Zhiliang Liu, Sibo Li, Xu Wang, Yuying Cui, Yuan Qin, Shifeng Leng, Yun-xiang Xu, Kai Yao, Haitao Huang

Graphical abstract

A lead‐bismuth (Pb‐Bi) binary metal based all‐inorganic perovskite film is successfully fabricated and applied as absorber layer to enhance the stability of perovskite solar cells (PSCs). High power conversion efficiency (PCE) of 11.9% is obtained for the all‐inorganic (PSC).The PCE only reduced by 10% under atmospheric humidity of 40% in 4 weeks.

Abstract

A lead‐bismuth (Pb‐Bi) binary metal based all‐inorganic perovskite film is successfully fabricated and applied as absorber layer to enhance the stability of perovskite solar cells (PSCs). Unlike the Pb‐only perovskite‐based device, the Pb‐Bi binary metal perovskite based one shows better tolerance to humidity and oxygen. High power conversion efficiency (PCE) of 11.9% is obtained for the all‐inorganic (PSC). Noticeably, the PCE only reduced by 10% under atmospheric humidity of 40% in four weeks. An electron‐only device also shows reduced trap states. The improved stability and PCE is ascribed to higher quality perovskite film with less trap states and smaller series resistance (R _s) in the device.

Sequentially processed organic photovoltaics (OPVs) using temperature‐dependent aggregation polymers where the acceptor materials have been processed using various nonorthogonal solvents provide almost similar performance in every single case. The superior performance when compared to their blend‐casting counterparts can be attributed to better control in morphology, which is critical for the large‐area scale‐up of OPVs.

Abstract

The conventional method to prepare bulk‐heterojunction organic photovoltaics (OPVs) is a one‐step method from the blend solution of donor and acceptor materials, known as blend‐casting (BC). Recently, an alternative method was demonstrated to achieve high efficiencies (13%) comparable to state‐of‐the‐art BC devices. This two‐step‐coating method, known as “sequential processing,” (SqP) involves sequential deposition of the donor and then the acceptor from two orthogonal solvents. However, the requirement of orthogonal solvents to process the donor and acceptor constrains the choice of materials and processing solvents. In this paper, an improved version of SqP method without the need for using orthogonal solvents is reported. The success is based on donor polymers with strong temperature‐dependent aggregation properties whose solution can be processed at a high temperature, but the resulting film becomes completely insoluble at room temperature, which allows for the processing of overlying acceptors from a wide range of nonorthogonal solvents. With this approach, efficient SqP OPVs is demonstrated based on a range of donor/acceptor materials and processing solvents, and, in every single case, SqP OPVs can outperform their BC counterparts. The results broaden the solvent choices and open a much larger window to optimize the processing parameters of SqP method.

O‐IDTBCN is a new nonfullerene acceptor that uses dicyanovinyl end groups to improve the electron mobility in blends with PTB7‐Th, relative to its predecessor, O‐IDTBR. Blends with O‐IDTBCN possess more balanced charge carrier mobilities, resulting in longer charge carrier lifetimes, which ultimately manifests in the attainment of fill factors of over 70% in devices.

Abstract

High fill factors have only recently become commonplace in nonfullerene‐based organic solar cells, with the balance of charge carrier mobilities often cited as the contributing factor. Here an end‐group modification to a commonly used nonfullerene acceptor (O‐IDTBR) is reported, in which the rhodanine end groups are replaced with dicyano moieties, resulting in the acceptor O‐IDTBCN. This new acceptor affords significant improvement in the fill factor (73%) and photocurrent (19.8 mA cm⁻²) in organic solar cells with the low bandgap polymer PTB7‐Th. A narrowing of the bandgap, as a result of greater push–pull hybridization, allows complementary absorption to the donor and thus improved photon harvesting. Additionally, the measurement of charge carrier mobilities and lifetimes in both systems reveal that the PTB7‐Th:O‐IDTBCN blend possesses more balanced charge carrier mobilities, and longer lifetimes. Morphology studies reveal a slightly greater degree of molecular mixing of the O‐IDTBCN when blended with PTB7‐Th, despite the greater and more balanced charge carrier mobilities in this blend.

High‐throughput density functional theory (DFT) methods are used to screen 1845 halide perovskite materials in search of nontoxic, stable, optimal bandgap materials with high photovoltaic efficiencies for use in single junction, quantum dot, and tandem Si‐perovskite solar cells. A total of 15 promising halide perovskite materials, including (CH₃NH₃)_0.75Cs_0.25SnI₃, ((NH₂)₂CH)Ag_0.5Sb_0.5Br₃, CsMn_0.875Fe_0.125I₃, ((CH₃)₂NH₂)Ag_0.5Bi_0.5I₃, and ((NH₂)₂CH)_0.5Rb_0.5SnI₃, are found.

Abstract

Two critical limitations of organic–inorganic lead halide perovskite materials for solar cells are their poor stability in humid environments and inclusion of toxic lead. In this study, high‐throughput density functional theory (DFT) methods are used to computationally model and screen 1845 halide perovskites in search of new materials without these limitations that are promising for solar cell applications. This study focuses on finding materials that are comprised of nontoxic elements, stable in a humid operating environment, and have an optimal bandgap for one of single junction, tandem Si‐perovskite, or quantum dot–based solar cells. Single junction materials are also screened on predicted single junction photovoltaic (PV) efficiencies exceeding 22.7%, which is the current highest reported PV efficiency for halide perovskites. Generally, these methods qualitatively reproduce the properties of known promising nontoxic halide perovskites that are either experimentally evaluated or predicted from theory. From a set of 1845 materials, 15 materials pass all screening criteria for single junction cell applications, 13 of which are not previously investigated, such as (CH₃NH₃)_0.75Cs_0.25SnI₃, ((NH₂)₂CH)Ag_0.5Sb_0.5Br₃, CsMn_0.875Fe_0.125I₃, ((CH₃)₂NH₂)Ag_0.5Bi_0.5I₃, and ((NH₂)₂CH)_0.5Rb_0.5SnI₃. These materials, together with others predicted in this study, may be promising candidate materials for stable, highly efficient, and nontoxic perovskite‐based solar cells.

This work reports a strategy that ensures the degree of nonradiative recombination can be measured accurately in low‐energetic‐offset organic photovoltaic systems and reports key observations on the relationship between the nonradiative recombination loss and properties of the donor/acceptor interface, including an observed correlation between high domain purity and high nonradiative recombination loss.

Abstract

Open‐circuit voltage (V _OC) losses in organic photovoltaics (OPVs) inhibit devices from reaching V _OC values comparable to the bandgap of the donor–acceptor blend. Specifically, nonradiative recombination losses (∆V _nr) are much greater in OPVs than in silicon or perovskite solar cells, yet the origins of this are not fully understood. To understand what makes a system have high or low loss, an investigation of the nonradiative recombination losses in a total of nine blend systems is carried out. An apparent relationship is observed between the relative domain purity of six blends and the degree of nonradiative recombination loss, where films exhibiting relatively less pure domains show lower ∆V _nr than films with higher domain purity. Additionally, it is shown that when paired with a fullerene acceptor, polymer donors which have bulky backbone units to inhibit close π–π stacking exhibit lower nonradiative recombination losses than in blends where the polymer can pack more closely. This work reports a strategy that ensures ∆V _nr can be measured accurately and reports key observations on the relationship between ∆V _nr and properties of the donor/acceptor interface.

The factors affecting the V _OC in 2D perovskite cells with different [PbI₆]⁴⁻ layer sheets (n = 2–4) are elucidated. Nonradiative recombination at the perovskite/C₆₀ interface is found to dominate except for the n = 2 system where the bulk recombination determines the properties of the cell. Substantial V _OC gains through suppression of interfacial recombination at the top interface are expected.

Abstract

2D Ruddlesden–Popper perovskite (RPP) solar cells have excellent environmental stability. However, the power conversion efficiency (PCE) of RPP cells remains inferior to 3D perovskite‐based cells. Herein, 2D (CH₃(CH₂)₃NH₃)₂(CH₃NH₃) _{n −1}Pb _n I_{3 n +1} perovskite cells with different numbers of [PbI₆]⁴⁻ sheets (n = 2–4) are analyzed. Photoluminescence quantum yield (PLQY) measurements show that nonradiative open‐circuit voltage (V _OC) losses outweigh radiative losses in materials with n > 2. The n = 3 and n = 4 films exhibit a higher PLQY than the standard 3D methylammonium lead iodide perovskite although this is accompanied by increased interfacial recombination at the top perovskite/C₆₀ interface. This tradeoff results in a similar PLQY in all devices, including the n = 2 system where the perovskite bulk dominates the recombination properties of the cell. In most cases the quasi‐Fermi level splitting matches the device V _OC within 20 meV, which indicates minimal recombination losses at the metal contacts. The results show that poor charge transport rather than exciton dissociation is the primary reason for the reduction in fill factor of the RPP devices. Optimized n = 4 RPP solar cells had PCEs of 13% with significant potential for further improvements.

Solution‐phase van der Waals epitaxy growth of MAPbI₃ perovskite films on MoS₂ flakes is observed. The in‐plane coupling between the perovskite and the MoS₂ crystal lattices leads to perovskite films with larger grain size, lower trap density, and preferential growth orientation. Consequently, the efficiency of fabricated perovskite solar cells is substantially improved by the MoS₂ flakes as interfacial layers.

Abstract

The quality of perovskite films is critical to the performance of perovskite solar cells. However, it is challenging to control the crystallinity and orientation of solution‐processed perovskite films. Here, solution‐phase van der Waals epitaxy growth of MAPbI₃ perovskite films on MoS₂ flakes is reported. Under transmission electron microscopy, in‐plane coupling between the perovskite and the MoS₂ crystal lattices is observed, leading to perovskite films with larger grain size, lower trap density, and preferential growth orientation along (110) normal to the MoS₂ surface. In perovskite solar cells, when perovskite active layers are grown on MoS₂ flakes coated on hole‐transport layers, the power conversion efficiency is substantially enhanced for 15%, relatively, due to the increased crystallinity of the perovskite layer and the improved hole extraction and transfer rate at the interface. This work paves a way for preparing high‐performance perovskite solar cells and other optoelectronic devices by introducing 2D materials as interfacial layers.

A thermodynamically favored crystal preferable orientation growth along the (001) crystal plane is explored in formamidinium/methylammonium mixed perovskites, and the origin is found to be the reduction of surface energy. Combined with the (001) plane lying parallel to the substrate, it affects the charge transportation and collection in the resultant perovskite solar cells, resulting in a power conversion efficiency of 21.2%.

Abstract

Crystal orientation has a great impact on the properties of perovskite films and the resultant device performance. Up to now, the exquisite control of crystal orientation (the preferred crystallographic planes and the crystal stacking mode with respect to the particular planes) in mixed‐cation perovskites has received limited success, and the underlying mechanism that governs device performance is still not clear. Here, a thermodynamically favored crystal orientation in formamidinium/methylammonium (FA/MA) mixed‐cation perovskites is finely tuned by composition engineering. Density functional theory calculations reveal that the FA/MA ratio affects the surface energy of the mixed perovskites, leading to the variation of preferential orientation consequently. The preferable growth along the (001) crystal plane, when lying parallel to the substrates, affects their charge transportation and collection properties. Under the optimized condition, the mixed‐cation perovskite (FA_{1– x} MA _x PbI_2.87Br_0.13 (Cl)) solar cells deliver a champion power conversion efficiency over 21%, with a certified efficiency of 20.50 ± 0.50%. The present work not only provides a vital step in understanding the intrinsic properties of mixed‐cation perovskites but also lays the foundation for further investigation and application in perovskite optoelectronics.

The combination of perylene diimide and fullerene results in a new hybrid as electron transporting material (ETM) in inverted perovskite solar cells. This hybrid ETM enables a high power conversion efficiency of 18.6 % and good device stability.

Abstract

Electron transport materials (ETM) play an important role in the improvement of efficiency and stability for inverted perovskite solar cells (PSCs). This work reports an efficient ETM, named PDI‐C₆₀, by the combination of perylene diimide (PDI) and fullerene. Compared to the traditional PCBM, this strategy endows PDI‐C₆₀ with slightly shallower energy level and higher electron mobility. As a result, the device based on PDI‐C₆₀ as electron transport layer (ETL) achieves high power conversion efficiency (PCE) of 18.6 %, which is significantly higher than those of the control devices of PCBM (16.6 %) and PDI (13.8 %). The high PCE of the PDI‐C₆₀‐based device can be attributed to the more matching energy level with the perovskite, more efficient charge extraction, transport, and reduced recombination rate. To the best of our knowledge, the PCE of 18.6 % is the highest value in the PSCs using PDI derivatives as ETLs. Moreover, the device with PDI‐C₆₀ as ETL exhibits better device stability due to the stronger hydrophobic properties of PDI‐C₆₀. The strategy using the PDI/fullerene hybrid provides insights for future molecular design of the efficient ETM for the inverted PSCs.

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.

Hexamethyl‐mono‐n‐butyl‐substituted zinc phthalocyanine (Me₆Bu‐ZnPc) is synthesized through a ring‐expansion method. The favored face‐on molecular alignment is observed for Me₆Bu‐ZnPc on the perovskite layer. Perovskite solar cells using Me₆Bu‐ZnPc as the dopant‐free hole‐transporting material achieve the highest power‐conversion efficiency (PCE) of 17.41% and retain over 90% of their initial PCE after 1400 h storage at 25 °C and with a relative humidity of 75%.

Efficient and stable hole‐transporting materials (HTMs) are necessary for perovskite solar cells (PSCs) with excellent efficiency and long‐term stability. Here, two A₃B‐type metal phthalocyanine (MPc) compounds are prepared as dopant‐free HTMs for conventional n‐i‐p structured PSCs. Mono‐n‐butyl‐substituted zinc phthalocyanine and hexamethyl‐mono‐n‐butyl‐substituted zinc phthalocyanine (Me₆Bu‐ZnPc) are synthesized through ring‐expansion method, and their exact structures are characterized using nuclear magnetic resonance and mass spectroscopy. The molecular orientation of the developed HTM thin films against the underlying surface is studied using X‐ray diffraction. Different substituents in MPcs can strongly affect their molecular orientation, resulting in different hole mobilities. The favored face‐on molecular alignment is only observed for Me₆Bu‐ZnPc on the perovskite layer, proving the crucial role of methyl substituents in controlling the molecular alignment through the special interactions between the MPc molecule and different sites of perovskite material on the surface. PSCs using Me₆Bu‐ZnPc as a dopant‐free HTM yields the highest reported power‐conversion efficiency (PCE) of 17.41%. With its high hydrophobicity and good coverage, Me₆Bu‐ZnPc HTM thin film acts as an encapsulation layer, which leads to significantly increased long‐term stability. The Me₆Bu‐ZnPc‐based devices retain over 90% of their initial PCE after 1400 h storage at 25 °C and with a relative humidity of 75%.

Surface treatments of SnO₂, such as UV–ozone (UVO) treatment, for 60 min, are shown to enhance efficiency and reduce hysteresis. UVO treatment improves contact charge selectivity, with a decrease in the recombination rate of the perovskite solar cells.

Tin oxide (SnO₂) is widely used as an electron transporting layer (ETL) in perovskite solar cells (PSCs) because of its good transparency, band alignment to perovskite, and stability. The interface between the ETL and the perovskite in the PSCs affects the charge extraction process and influences the optoelectronic properties. Surface treatment of SnO₂, such as the UV–ozone (UVO) treatment, is shown to enhance the efficiency and reduce the light soaking effect of the PSCs. Herein, the success in control and suppressing hysteresis reaching the highest photoconversion efficiency of 19.4% with negligible hysteresis for the growth of the devices on SnO₂ treated with UVO for 60 min is reported. The wettability of the treated SnO₂ is well matched with the polar solvent of the perovskite solution, leading to complete coverage of the substrate, although the treatment does not affect the morphology and the crystallinity of the perovskite thin films. Impedance spectroscopy measurement analysis clearly indicates the decrease in the recombination rate after the UVO treatment and the reduction in low frequency capacitance causing a reduction in the current–potential curve hysteresis.

Electric field treatment during thermal annealing is used to control the vertical phase segregation of components in the organic solar cells. Residual additive solvent remaining in the active layer, which is responsible for unfavorable morphological changes, is effectively removed by this treatment. Maintaining the morphology of the active layer over time reflects long‐term stability of solar cells.

The utility of electric fields during the bulk heterojunction (BHJ) film drying process for tuning the morphology and stability of the device is demonstrated. An external electric‐field‐assisted annealing (EFTA) treatment is used to engineer the stability of amorphous donor polymer‐based BHJs without compromising device performance. Residual additive in the device post fabrication is a major source of degradation. Thermal annealing of an active layer effectively removes residual additive, which in case of amorphous polymer donor‐based BHJs, however, leads to unfavorable changes in the morphology. The detrimental effect of thermal annealing in amorphous donor polymer‐based solar cells is mitigated by the presence of an electric field during the drying stage. The complete removal of additive is ensured by this treatment procedure and leads to improved packing and a rigid morphology. The structural stability is reflected in the performance parameters monitored over the long term and electrical noise measurements. The magnitude and polarity of the applied electric field are observed to control the vertical distribution of donor and acceptor components.

An asymmetric crystal growth method is described for the synthesis of mixed‐cation perovskite single‐crystal micro‐plates. The thickness of the crystals is controlled by the difference between the thicknesses of the two spacers. The surface of the spaces weakens the attraction between the gap and the precursor complexes, thereby relieving the limit imposed by the low diffusion rate of the precursor ions.

The synthesis of certain asymmetric perovskite single crystals (SCs)—including CH₃NH₃PbI₃, which is used most commonly—for application in high‐performance perovskite solar cells (PeSCs), remains very challenging. Herein, a promising but general method, differential space‐limited crystallization (DSLC), is described for synthesizing high‐quality perovskite single‐crystal micro‐plates. The thickness of the perovskite SCs is controlled by the difference between the thicknesses of two sets of polytetrafluoroethylene (PTFE) spacers. Because the DSLC method does not require very thin spacers, it simplifies the procedure of crystal growth. More importantly, the hydrophobicity of the PTFE spacers weakens the attraction between the surfaces of the confined space and the precursor complexes, thereby increasing the rate of diffusion of the precursor ions. Accordingly, the critical nucleation step is not limited by the low rate of diffusion of the ions. This approach is used to prepare mixed‐cation lead iodide single‐crystalline micro‐plates for solar cell applications. The device performance of single‐crystal PeSCs improves after introducing formamidinium ions. The stability of the single‐crystal devices also improves relative to that of conventional thin‐film counterparts. It is anticipated that this DSLC method can also be used to synthesize different types of asymmetrical perovskite SCs for other optoelectronic applications.

A series of new spiro‐arranged hole‐transporting materials based on an orthogonal dibenzosuberene core unit incorporated with substituted phenylpyrazole are synthesized, namely, THY‐1 to THY‐5. The THY‐5 exhibits almost identical photovoltaic performance when compared with spiro‐OMeTAD, because of its homogeneous film morphology, which is attributed to the presence of bulky ^tBu and hydrophobic CF₃ moieties, facilitating the solubility in the casting solvent.

A series of spiro‐arranged hole‐transporting materials are designed and synthesized by incorporating a substituted phenylpyrazole unit to the orthogonal dibenzosuberene core unit, which are named as THY‐1 to THY‐5. All of them exhibit good optical, electrochemical, and electronic properties as needed for HTMs, despite the distinctive morphologies observed for the spin‐casted thin film. A perovskite solar cell based on THY‐5 exhibits the highest power conversion efficiency of 15.83%, which is comparable to that of the N2,N2,N2′,N2′,N7,N7,N7′,N7′‐octakis(4‐methoxyphenyl)‐9,9′‐spirobi[9H‐fluorene]‐2,2′,7,7′‐tetramine (Spiro‐OMeTAD) reference device (16.22%) fabricated using identical architecture.

The performance of inverted perovskite solar cells (i‐PSCs) is significantly improved using bulk‐heterojunction electron transport layers. The high efficiency originates from reduced trap‐assistant recombination due to the shortened electron capture region, high electron mobility, and suitable energy level of electron transport layers. The ultrahigh stability is attributed to effectively prevented moisture permeation due to more hydrophobic electron transport layers.

The power conversion efficiency (PCE) of inverted perovskite solar cells (i‐PSCs) is lower than that of the normal structures. The low efficiency is mainly ascribed to the inferior properties of commonly used [6,6]‐phenyl C61 butyric acid methyl ester (PCBM) electron transport layers (ETLs) such as complexity in achieving high‐quality films, low electron mobility, imperfect energy level for electron extraction, and large electron capture region. Herein, the bulk heterojunction (BHJ) ETLs composed of PCBM and polymers are developed. The electron mobility of the BHJ film is enhanced by more than three times compared with PCBM, leading to efficient electron extraction. The electron capture region of the BHJ film decreases to 1.20 × 10⁻¹⁸ from 3.70 × 10⁻¹⁷ cm⁻³ for PCBM due to increased relative permittivity, which reduces the trap‐assistant recombination at the interface. Meanwhile, the devices with BHJ exhibit good stability regardless of illumination and dark storage conditions owing to the more hydrophobic BHJ films and full coverage of perovskite surface, which effectively prevent the moisture permeation into the perovskite devices. It is believed that this breakthrough provides a suitable approach to improve the efficiency and stability of i‐PSCs.

Eliminating the use of toxic, halogenated antisolvents in perovskite film preparation has been long desired. This work demonstrates the use of a halogen‐free, mixed antisolvent composed of ethyl acetate and hexane to boost the efficiency of tin oxide (SnO₂)–triple cation system beyond 20% without the use of an additional passivation layer.

Abstract

Solution‐processed triple‐cation perovskite solar cells (PSCs) rely on complex compositional engineering or delicate interfacial passivation to balance the trade‐off between cell efficiency and long‐term stability. Herein, the facile fabrication of highly efficient, stable, and hysteresis‐free tin oxide (SnO₂)‐based PSCs is demonstrated with a champion cell efficiency of 20.06% using a green, halogen‐free antisolvent. The antisolvent, composed of ethyl acetate (EA) solvent and hexane (Hex) in different proportions, works exquisitely in regulating perovskite crystal growth and passivating grain boundaries, leading to the formation of a crack‐free perovskite film with enlarged grain size. The high quality perovskite film inhibits carrier recombination and substantially improves the cell efficiency, without requiring an additional enhancer/passivation layer. Furthermore, these PSCs also demonstrate remarkable long‐term stability, whereby unencapsulated cells exhibit a power conversion efficiency (PCE) retention of ≈71% after >1500 hours of storage under ambient condition. For encapsulated cells, an astounding PCE retention of >98% is recorded after >3000 hours of storage in air. Overall, this work realizes the fabrication of SnO₂‐based PSCs with a performance greater or comparable to the state‐of‐the‐art PSCs produced with halogenated antisolvents. Evidently, EA–Hex antisolvent can be an extraordinary halogen‐free alternative in maximizing the performance of PSCs.

Preventing the degradation of metal perovskite solar cells (PSCs) by humid air poses a substantial challenge for their future deployment. We introduce here a two-dimensional (2D) A₂PbI₄ perovskite layer using pentafluorophenylethylammonium (FEA) as a fluoroarene cation inserted between the 3D light-harvesting perovskite film and the hole-transporting material (HTM). The perfluorinated benzene moiety confers an ultrahydrophobic character to the spacer layer, protecting the perovskite light-harvesting material from ambient moisture while mitigating ionic diffusion in the device. Unsealed 3D/2D PSCs retain 90% of their efficiency during photovoltaic operation for 1000 hours in humid air under simulated sunlight. Remarkably, the 2D layer also enhances interfacial hole extraction, suppressing nonradiative carrier recombination and enabling a power conversion efficiency (PCE) >22%, the highest reported for 3D/2D architectures. Our new approach provides water- and heat-resistant operationally stable PSCs with a record-level PCE.

Nature Communications, Published online: 07 June 2019; doi:10.1038/s41467-019-10351-5

Nature Communications, Published online: 07 June 2019; doi:10.1038/s41467-019-10434-3