JIALINGBO

A record efficiency is achieved for wide-band gap perovskite solar cell via a surface gradient passivation strategy. It is found that increasing the distance between F and −NH₃ ⁺ of fluorinated ammonium can enhance the electropositivity of −NH₃ ⁺, thus providing strong adsorption onto the I_A and I_Pb anti-site defects to suppress non-radiative recombination. Consequently, the p-FPEAI (para-Fluorophenylethylammonium Iodide) modified device affords a record-efficiency of 21.63 %.

Abstract

Wide-band gap (1.68 eV) perovskite solar cells (PSCs) are important components of perovskite/Si tandem devices. However, the efficiency of wide band gap PSCs has been limited by their huge open-circuit voltage (V _oc) deficit due to non-radiative recombination. Deep-level acceptor defects are identified as the major killers of V _oc, and they can be effectively improved by passivation with ammonium salts. Theoretical calculation predicts that increasing the distance between F and −NH₃ ⁺ of fluorinated ammonium can dramatically enhance the electropositivity of −NH₃ ⁺ terminals, thus providing strong adsorption onto the negatively charged I_A and I_Pb anti-site defects. Characterizations further confirm that surface gradient passivation employing p-FPEAI demonstrates the most efficient passivation effect. Consequently, a record-efficiency of 21.63 % with the smallest V _oc deficit of 441 mV is achieved for 1.68 eV-band gap inverted PSCs. Additionally, a flexible PSC and 1 cm² opaque device also deliver the highest PCEs of 21.02 % and 19.31 %, respectively.

An electron-deficient tetrafluoronaphthodithiophene (FNT) was created to construct a family of PFNT-F/Cl polymers for organic solar cells. The PFNT-F/Cl-based OSCs exhibit impressive FF values of 0.80, and remarkable PCEs of 17.53 % and 18.10 %, suggesting multifluorinated polymers are promising donor materials for non-fullerene OSCs.

Abstract

Creating new electron-deficient unit is highly demanded to develop high-performance polymer donors for non-fullerene organic solar cells (OSCs). Herein, we reported a multifluorinated unit 4,5,6,7-tetrafluoronaphtho[2,1-b : 3,4-b′]dithio-phene (FNT) and its polymers PFNT-F and PFNT-Cl. The advantages of multifluorination: (1) it enables the polymers to exhibit low-lying HOMO (≈−5.5 eV) and wide band gap (≈2.0 eV); (2) the short interactions (F⋅⋅⋅H, F⋅⋅⋅F) endow the polymers with properties of high film crystallinity and efficient hole transport; (3) well miscibility with NFAs that leads to a more well-defined nanofibrous morphology and face-on orientation in the blend films. Therefore, the PFNT-F/Cl : N3 based OSCs exhibit impressive FF values of 0.80, and remarkable PCEs of 17.53 % and 18.10 %, which make them ranked the best donor materials in OSCs. This work offers new insights into the rational design of high-performance polymers by multifluorination strategy.

Alkylammonium in the form of CH₃NH₃ ⁺ is produced in the reaction between CH₃NH₂ and dissociated 2H₂O molecules via the catalytic halide anion in a hybrid perovskite precursor. This stabilization of alkylammonium is largely dependent on the quantity of the ionized halide additive and its proton affinity. Consequently, the stabilized alkylammonium can produce stable and more ordered organic–inorganic metal trihalide perovskite crystals.

Abstract

The development of alkylammonium lead trihalide perovskite (ALHP) photovoltaics has grown rapidly over the past decade. However, there are remaining critical challenges, such as proton defects, which can lead to the material instability of ALHPs. Although specific strategies, including the use of halide additives, have significantly reduced the defects, a fundamental understanding of the defect passivation mechanism remains elusive. Herein, an approach and mechanism for minimizing proton defects in ALHP crystals by adding ionized halides to the perovskite precursor solution are reported. This work clarifies that the ionized halides induced proton transfer from H₂O to the alkylammonium cation in the precursor solution, stabilizing the ALHP crystals. The fundamental characteristics of ALHP and its precursors are examined by X-ray diffraction, transmittance electron microscopy, in situ extended X-ray absorption fine structure, Fourier transform NMR spectroscopy, and Fourier transform infrared spectroscopy. The findings from this work will guide the development of highly stable ALHP crystals, enabling efficient and stable optoelectronic ALHP devices.

This work first designed and synthesized metal-free MPAZE-NH₄I₃ ⋅ H₂O perovskites by introducing bulk methyl groups to improve tolerance factor and enhance hydrogen bonds for improving its stability and performance. Importantly, the related flexible X-ray detector shows the highest sensitivity of 740.8 μC Gy_air ⁻¹ cm⁻², and promises to realize non-toxic degradation, mechanical bending stability and array imaging for future application.

Abstract

Metal-free perovskites (MFPs) with flexible and degradable properties have been adopted in flexible X-ray detection. For now, figuring out the key factors between structure and device performance are critical to guide the design of MFPs. Herein, MPAZE-NH₄I₃ ⋅ H₂O was first designed and synthesized with improved structural stability and device performance. Through theoretical calculations, the introducing methyl group benefits modulating tolerance factor, increases dipole moment and strengthens hydrogen bonds. Meanwhile, H₂O increases the hydrogen bond formation sites and synergistically realizes the band nature modulation, ionic migration inhibition and structural stiffness optimization. Spectra analysis also proves that the improved electron-phonon coupling and carrier recombination lifetime contribute to enhanced performance. Finally, a flexible and degradable X-ray detector was fabricated with the highest sensitivity of 740.8 μC Gy_air ⁻¹ cm⁻² and low detection limit (0.14 nGy_air s⁻¹).

Aniline sulfonic acid with dual sites is utilized to cure excess/unreacted lead iodide in perovskite films. The introduction of additives can induce a uniform growth of perovskite seeds on the substrate, which aids the growth of high-quality and uniform perovskite films. The fabricated perovskite photovoltaics deliver maximum power conversion efficiency of 24.09% (0.09 cm²) and 20.87% (16 cm²), respectively.

Abstract

Unreacted/excess lead iodide is considered to be the archcriminal for the rapid degradation of hybrid perovskite solar cells. Meanwhile, a high-quality perovskite film with uniform and large grain size is the basis for high-performance perovskite modules. Herein, a dual-site molecular additive 4-Aniline Sulfonic Acid (4A) is developed to regulate the unreacted/excess PbI₂ and passivate defects through hydrogen bonding and intermolecular interactions between amino, and a sulfate groups and PbI₂, respectively. Furthermore, the introduction of the 4A additive can induce perovskite seeds to grow uniformly on the substrate, yielding dense, uniform and defect-less perovskite films with large grain sizes. This enables the fabrication of perovskite photovoltaics with a maximum power conversion efficiency of 24.09% (0.09 cm²) and 20.87% (16 cm²), respectively. This work demonstrated a new strategy to deposit high-quality large-scale perovskite films for photovoltaic modules.

This study suggests that the general use of phenethylamine-based interlayers results in the degradation of perovskite. Focusing on these degradation mechanisms, poly(methyl methacrylate) (PMMA) is a breakthrough in preventing direct contact between perovskite (PVK) and phenethylamine halides (PEAX). The PMMA/PEAX double interlayer is effective for both stability and efficiency of the perovskite solar cell, and heat treatment (PMMA/H-PEABr) maximizes overall performance.

Phenethylamine (PEA) halides (X) coated on perovskite (PVK) films are widely known as passivating layers, resulting in high performance in perovskite solar cells (PSCs). However, critical stability issues associated with phenethylamine halides (PEAX) in PSCs are observed, especially with Spiro-OMeTAD, which prevented its practical use. Here, the mechanism by which PEAX negatively affects PSCs is reported. In addition, a method is devised to overcome the stability issue by employing poly(methyl methacrylate) (PMMA) at the PVK/PEABr interface to form dual PMMA/PEABr interlayers. Contrary to the general use of PEABr, the indirect contact of PEABr with PVK films by PMMA resulted in superior power conversion efficiencies (PCEs) and enhanced stability resulting from the retention of dipole moments even under aging. Further, effective methods of maximizing and retaining the dipole effect by heating PMMA/PEAX, as opposed to PSCs incorporating PEAX without PMMA being negatively affected by heat are exploited. The resulting PSCs with PMMA/heated PEABr exhibit a PCE of 21.63%, and retain 95% of their original performance a month after fabrication.

Deposition of hole transport layers that utilize self-assembled monolayers (SAM-HTLs) has thus far been limited to solution-based methods. Development of alternative scalable deposition methods, such as vacuum-based evaporation techniques, is crucial to improve process flexibility. For the first time, physical vapor deposition (PVD) via thermal evaporation of widely known SAM-HTLs (2PACz, MeO-2PACz, and Me-4PACz) is reported and incorporated into p-i-n perovskite solar cells.

Abstract

Engineering of the interface between perovskite absorber thin films and charge transport layers has fueled the development of perovskite solar cells (PSCs) over the past decade. For p-i-n PSCs, the development and adoption of hole transport layers utilizing self-assembled monolayers (SAM-HTLs) based on carbazole functional groups with phosphonic acid anchoring groups has enabled almost lossless contacts, minimizing interfacial recombination to advance power conversion efficiency in single-junction and tandem solar cells. However, so far these materials have been deposited exclusively via solution-based methods. Here, for the first time, vacuum-based evaporation of the most common carbazole-based SAM-HTLs (2PACz, MeO-2PACz, and Me-4PACz) is reported. X-ray photoelectron spectroscopy and infrared spectroscopy demonstrate no observable chemical differences in the evaporated SAMs compared to solution-processed counterparts. Consequently, the near lossless interfacial properties are either preserved or even slightly improved as demonstrated via photoluminescence measurements and an enhancement in open-circuit voltage. Strikingly, applying evaporated SAM-HTLs to complete PSCs demonstrates comparable performance to their solution-processed counterparts. Furthermore, vacuum deposition is found to improve perovskite wetting and fabrication yield on previously non-ideal materials (namely Me-4PACz) and to display conformal and high-quality coating of micrometer-sized textured surfaces, improving the versatility of these materials without sacrificing their beneficial properties.

Herein, an anion-engineered additive strategy is reported to modify the crystallization process of perovskite films on industrially feasible double-side textured silicon, which enables conformal deposition with improved film crystallinity and reduced trap density. This allows the fabrication of perovskite/silicon tandem solar cells with efficiencies of 28.9% (certified efficiency of 27.9%) and 25.1% for areas of 1 and 16 cm², respectively.

Abstract

Monolithic perovskite/silicon tandem solar cells promise power-conversion efficiencies (PCEs) exceeding the Shockley-Queisser limit of single-junction solar cells. The conformal deposition of perovskites on industrially feasible textured silicon solar cells allows for both lowered manufacturing costs and a higher matched photocurrent density, compared to state-of-the-art tandems using front-side flat or mildly textured silicon. However, the inferior crystal quality of perovskite films grown on fully-textured silicon compromises the photovoltaic performance. Here, an anion-engineered additive strategy is developed to control the crystallization process of wide-bandgap perovskite films, which enables improved film crystallinity, reduced trap density, and conformal deposition on industrially textured silicon. This strategy allows the fabrication of 28.6%-efficient perovskite/silicon heterojunction tandem solar cells (certified 27.9%, 1 cm²). This approach is compatible with the scalable fabrication of tandems on industrially textured silicon, demonstrating an efficiency of 25.1% for an aperture area of 16 cm². The anion-engineered additive significantly improves the operating stability of wide-bandgap perovskite solar cells, and the encapsulated tandem solar cells retain over 80% of their initial performance following 2000 h of operation under full 1-sun illumination in ambient conditions.

By employing pre-synthesized 3D methylammonium lead chloride (MAPbCl₃) and 1D 2-aminobenzothiazole lead iodide (ABTPbI₃) microcrystals into a self-drying perovskite precursor, this work successfully modifies the crystallization process without antisolvents and reduces defects at grain boundaries. Furthermore, the best-performing inverted device exhibits a champion power conversion efficiency of 23.27% for small-area devices (0.09 cm²) and 21.52% for large-area devices (1.0 cm²).

Abstract

Developing a facile method to prepare high-quality perovskite films without using the antisolvent technique is critical for upscaling production of perovskite solar cells (PVSCs). However, the as-prepared formamidinium (FA)-based perovskite films often exhibit poor film quality with high density of defects if antisolvent is not used, limiting the photovoltaic performance and long-term stability of derived PVSCs. Herein, this work adopts pre-synthesized 3D methylammonium lead chloride (MAPbCl₃) and 1D 2-aminobenzothiazole lead iodide (ABTPbI₃) microcrystals into self-drying perovskite precursors, which serve as seed crystals to promote nucleation and growth of FAPbI₃-based perovskites without requiring antisolvent extraction. The combined binary microcrystals facilitate the formation of a dense and pinhole-free perovskite film with a stable perovskite lattice and defect-healed grain boundaries, enabling efficient charge carrier transfer and reduced non-radiative recombination loss. As a result, the best-performing inverted architecture device exhibits a champion power conversion efficiency of 23.27% for small-area devices (0.09 cm²) and 21.52% for large-area devices (1.0 cm²). These values are among the highest efficiencies reported for antisolvent-free PVSCs. Additionally, the unencapsulated device shows enhanced moisture, thermal, and operational stabilities, and maintains 92% of its initial efficiency after being held at the maximum power point for 1000 h.

Inverted perovskite solar cells with [(C₈H₁₇)₄N]₄[SiW₁₂O₄₀] (TOASiW₁₂)-modified Al as the cathode present not only the power conversion efficiency of 20.64% but also good air stability because TOASiW₁₂ suppresses Al corrosion and perovskite decomposition by blocking the moisture into the perovskite and catching mobile Al atoms to form AlO_x and prevent the Al atoms invading the perovskite.

Abstract

Inexpensive metal Al is scarcely utilized as the cathode in the perovskite solar cells (PVSCs) because its violent reaction with perovskite active layer results in poor device stability in air. It is urgent to improve the efficiency and stability of PVSCs with Al as the cathode for mass production of low-cost PVSCs. Herein, a novel solution-processed cathode interlayer material, surfactant-encapsulated polyoxometalate complex [(C₈H₁₇)₄N]₄[SiW₁₂O₄₀] (TOASiW₁₂) is reported. Using TOASiW₁₂-modified Al as the cathode, the power conversion efficiency (PCE) of 20.64% has been achieved in the inverted PVSCs. The findings demonstrate that a thin TOASiW₁₂ layer can effectively obstruct the chemical reaction between Al and perovskite layer, and significantly enhance the device stability. The unencapsulated devices with TOASiW₁₂-modified Al retain more than 80% of the initial PCE after 350 h storage in the ambient atmosphere at 45% relative humidity. This study provides an excellent alternative cathode interlayer material for efficient and stable inverted PVSCs.

A new pyridine-based polymer hole-transporting material is developed through backbone engineering strategy to simultaneously modulate the interface and crystallinity of inverted perovskite solar cells, resulting in a remarkable power conversion efficiency of 24.89% (certified 24.50%) with outstanding stability.

Abstract

The interface and crystallinity of perovskite films play a decisive role in determining the device performance, which is significantly influenced by the bottom hole-transporting material (HTM) of inverted perovskite solar cells (PVSCs). Herein, a simple design strategy of polymer HTMs is reported, which can modulate the wettability and promote the anchoring by introducing pyridine units into the polyarylamine backbone, so as to realize efficient and stable inverted PVSCs. The HTM properties can be effectively modified by varying the linkage sites of pyridine units, and 3,5-linked PTAA-P1 particularly demonstrates a more regulated molecular configuration for interacting with perovskites, leading to highly crystalline perovskite films with uniform back contact and reduced defect density. Dopant-free PTAA-P1-based inverted PVSCs have realized remarkable efficiencies of 24.89% (certified value: 24.50%) for small-area (0.08 cm²) as well as 23.12% for large-area (1 cm²) devices. Moreover, the unencapsulated device maintains over 93% of its initial efficiency after 800 h of maximum power point tracking under simulated AM 1.5G illumination.

Bottom Al₂O₃ and top poly (methyl methacrylate) (PMMA) passivations are adopted to improve the performance of the 2D perovskite-based photodiode. Much suppressed dark current and increased photocurrent are obtained by Al₂O₃ passivation. Device stability is improved by PMMA passivation. Responsivity and detectivity reach 0.36 A W⁻¹ and 5.4 × 10¹² Jones under 532 nm laser illumination at a power density of 1.5 nW cm⁻².

Abstract

2D perovskites have attracted intensive attention by virtue of their excellent optical and electrical properties along with good stabilities. Herein, a highly sensitive self-powered photodiode based on (PEA)₂(MA)₄Pb₅I₁₆ (PEA=C₆H₅(CH₂)NH₃, MA=CH₃NH₃) 2D perovskite is demonstrated by dual interface passivations. The Al₂O₃ bottom passivation can reduce the pinhole defects in the 2D perovskite film and suppress the trap-related recombination loss, bringing forward much reduced dark current and increased photocurrent. The poly (methyl methacrylate) (PMMA) top passivation can encapsulate the 2D perovskite film and thus improve the stability of the device. These results show that the 2D perovskite-based photodiode with dual interface passivations exhibits a large photo-to-dark current ratio of 10⁷, a fast response speed of 597 ns and a linear dynamic range of 160 dB without bias. Responsivity (R) and detectivity (D*) respectively reach 0.36 A W⁻¹ and 5.4 × 10¹² Jones under 532 nm laser illumination at a power density of 1.5 nW cm⁻². Moreover, the dual interface passivated device exhibits good stabilities. This study paves the road for developing low-cost, low-power, solution processed image sensors.

The excellent photoelectric performance, simple preparation process, and potentially extremely low preparation cost of halide perovskites not only attract the attention of a large number of researchers but also obtain the favor from industry. This review summarizes the latest progress of perovskite for X-ray detection in the past 10 years, identifies the challenges, and suggests the main research directions in future.

Abstract

Composition engineering, with its advantages to effectively tune semiconductor properties by regulating chemical stoichiometry, is a proven strategy to boost the efficiency and stability of ABX₃ perovskite photoelectronic devices. Compared with its counterpart polycrystalline perovskite film, single crystalline is the ideal model for exploring its fundamental scientific issues. In this review, a critical overview of recent advances of the growth strategies, properties, and functional applications of multicomponent perovskite single crystals (SCs) is presented. First, the underlying advantages of composition engineering of perovskite SCs are discussed and then the different composition tuning strategies, including A-site, B-site, X-site, and simultaneous A- and X-site engineering, are systematically summarized. Subsequently, the benefits of composition engineering are highlighted for optimizing photovoltaic and photoelectronic devices. Lastly, controversies and remaining challenges for the development of composition engineering of perovskite SCs are discussed and a brief perspective regarding further investigation in this field is provided.

Structure-dependent effects of the four fullerene bisadduct regioisomers on the device performance of tin-based perovskite solar cells are systemically investigated. Benefiting from the favorable molecular packing, energy level alignment, and interfacial interaction, the trans-3-based devices yield a champion efficiency of 14.58% with a certified efficiency of 14.30%, representing one of the best-performing tin-based devices.

Abstract

Tin-based perovskite solar cells (TPSCs) are attracting intense research interest due to their excellent optoelectric properties and eco-friendly features. To further improve the device performance, developing new fullerene derivatives as electron transporter layers (ETLs) is highly demanded. Four well-defined regioisomers (trans-2, trans-3, trans-4, and e) of diethylmalonate-C₆₀ bisadduct (DCBA) are isolated and well characterized. The well-defined molecular structure enables us to investigate the real structure-dependent effects on photovoltaic performance. It is found that the chemical structures of the regioisomers not only affect their energy levels, but also lead to significant differences in their molecular packings and interfacial contacts. As a result, the devices with trans-2, trans-3, trans-4, and e as ETLs yield efficiencies of 11.69%, 14.58%, 12.59%, and 10.55%, respectively, which are higher than that of the as-prepared DCBA-based (10.28%) device. Notably, the trans-3-based device also demonstrates a certified efficiency of 14.30%, representing one of the best-performing TPSCs.

Molten salt strategy enables the fabrication of perovskite solar cells by two-step sequential vacuum evaporation with exceptional reproducibility. The PSCs yield power conversion efficiencies of ≈24% and have good operational stability and shelf-life stability. The strategy has good expansibility in fabricating PSCs with tunable bandgaps.

Abstract

Vacuum evaporation is promising for the scalable fabrication of perovskite solar cells (PSCs). Nevertheless, the poor thermal conductivity of metal halide powder leads to unfavorable temperature inhomogeneity, which destabilizes the evaporation rate, posing a major challenge to the reproducible deposition of perovskite films, particularly by coevaporation. Herein, a molten salt strategy is reported for sequentially vacuum evaporation of PSCs. The molten salt increases the thermal conductivity of metal halides and greatly homogenizes the temperature, which stabilizes the evaporation rate and the composition of the resulting perovskite films. The PSCs yield power conversion efficiencies (PCEs) of ≈24% with exceptional reproducibility. The unencapsulated PSCs maintain 85% of the initial PCE after 3600 h of maximum power point tracking and maintain 85% of the initial PCE after being heated at 60 °C for 3000 h. The molten salt strategy opens a new avenue for the application of evaporation in perovskite optoelectronics.

Passivation and contact performance of double-textured tunnel oxide passivating contact (TOPCon) structures are promoted by rearranging the schedules of annealing processes and radio frequency powers of depositing SiO _x films, and the underlying mechanisms of charge-carrier transport on the textured structures are closely studied. The proof-of-concept perovskite/TOPCon tandem solar cells featuring double-textured structures are fabricated, yielding an outstanding efficiency of 28.49%.

Abstract

The ongoing success of tunnel oxide passivating contact (TOPCon) solar cells in the photovoltaic community in conjunction with the continuous advancements in the fabrication technologies of perovskite-based tandem devices make it possible to access highly-efficient perovskite/TOPCon tandem solar cells (TSCs). However, the development of such tandem solar cells is still in its infancy. One of the main challenges facing these devices is the balance of passivation and contact properties, especially on the textured crystalline silicon substrates. This article focuses on the double-textured TOPCon structures, and systematically investigates their passivation and contact properties with the purpose of balancing charge-carrier recombination and transport properties. The experiment results show that passivation and contact properties of the double-textured TOPCon structures can be well-regulated by means of rearranging the schedules of annealing processes and radio frequency powers of SiO _x deposition. The mechanisms of charge-carrier transport on the textured structures are closely studied, suggesting that charge carriers prefer to transport via the valleys of pyramids where the SiO _x layer is thin or missing. As a result, the proof-of-concept perovskite/TOPCon TSCs featuring the double-textured structures are successfully fabricated with a remarkable efficiency of 28.49%.