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Inverted perovskite solar cells (IPSCs) have attracted unprecedented attention due to their negligible hysteresis, long‐term operational stability, low temperature, and cost‐effective fabrication process, as well as wide applications. The power conversion efficiency (PCE) of IPSCs has skyrocketed from 3.9% in 2013 to certified 26.1% in 2023, which is over the certified 25.8% of regular counterpart, benefiting from the emergence of a great number of organic hole‐transporting materials (HTM). This review provides an overview of the recent development of organic hole‐transporting materials in the efficiency and stability of IPSCs, including organic small molecules and conjugated conductive polymers. The effective strategies for the charge‐transport layer and perovskite films of IPSCs are also discussed. Finally, the prospective for further development of IPSCs is outlined, including developing novel hole‐transporting materials and fabricating techniques to meet the requirements of commercial application. [ABSTRACT FROM AUTHOR]

To simultaneously stabilize cesium lead triiodide (CsPbI3) precursor solution and passivate the defects in CsPbI3 film is greatly significant for achieving highly stable and efficient CsPbI3 perovskite solar cells (PSCs). Herein, an effective redox 4‐fluorobenzothiohydrazide (FBTH) is developed to stabilize the precursor solution and passivate iodine/lead‐related defects for high‐quality CsPbI3 film. The comprehensive research confirms that 1) a new compound FBTH‐I is obtained from an effective redox interaction between FBTH and molecular iodine (I2) in perovskite precursor solution, which can effectively impede the formation of I2 molecule and restrain I− migration in perovskite film by forming N–H···I bond; 2) FBTH‐I can also passivate Pb‐related defects via forming S···Pb interaction. Consequently, the CsPbI3 PSC based on FBTH‐treated precursor solution exhibits a fascinating power conversion efficiency (PCE) of 21.41%, which is one of the highest PCE values among the reported pure CsPbI3 PSCs so far, and an outstanding stability against the harsh conditions, such as thermal annealing and continuous light‐illumination. [ABSTRACT FROM AUTHOR]

Although the power conversion efficiency (PCE) of perovskite solar cells (PSCs) is 26.1%, their stability is still a roadblock for large‐scale commercialization. In the initial density‐functional theory research, it is shown that the most damaging type of defect that destroys device performance is undercoordinated Pb2+ on the surface of the perovskite thin film. An ultraviolet‐absorbent material, 2‐hydroxybenzophenone (HBP), is utilized to specifically passivate this type of defect. In theoretical studies, it is shown that it effectively binds to the undercoordinated Pb2+ via its –C═O group. It also passivates I−‐related defects by forming a hydrogen bond using its –OH group, resulting in decreased trap density and hence prolonged carrier lifetime. The HBP can absorb ultraviolet irradiation, leading to much‐reduced UV degradation; its hydrophobic benzene rings protect the perovskite from moisture permeation. As a result, the constructed device reaches a high PCE of 16.39% with superior stability. The bare device maintains 80.4% of its initial PCE after exposure to ambient air for 792 h. In comparison, the control device without HBP retains only 63.2% of its initial efficiency. Under UV irradiation (80 mW cm−2, 365 nm) for 13 h, the former retains 77.9% of its initial PCE while the control device lost 52% of its initial value. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskite solar cells (PSCs) have been the research focus due to their high thermal stability and proper band gap for tandem solar cells. However, their power conversion efficiency (PCE) is still lower than that of organic‐inorganic hybrid PSCs. Herein, a sacrificing dye (Rhodamine B isothiocyanate, RBITC) is developed to regulate the growth of perovskite film by in situ release of ethylammonium cations, isothiocyanate anions and benzoic acid molecules upon annealing and illumination. The ethylammonium cations can efficiently passivate surface defects. The isothiocyanate anions incorporate with uncoordinated Pb to regulate the crystallization process. The benzoic acid molecules facilitate the nucleation of the perovskite crystals. Especially, the illumination can accelerate the release of these beneficial ions/molecules to improve the quality of perovskite films further. After optimization with RBITC, a high open circuit voltage (VOC) of 1.24 V and a champion PCE of 20.95% are obtained, which are among the highest Voc and PCE values of CsPbI3 PSCs. Accordingly, the operational stability of the PSC devices is significantly improved. The results provide an efficient chemical strategy to regulate the formation of perovskite films in whole crystallization process for high performance all‐inorganic PSCs. [ABSTRACT FROM AUTHOR]

The poor interface quality between cesium lead triiodide (CsPbI3) perovskite and the electron transport layer limits the stability and efficiency of CsPbI3 perovskite solar cells (PSCs). Herein, a 4‐amino‐2,3,5,6‐tetrafluorobenzoate cesium (ATFC) is designed as a bifacial defect passivator to tailor the perovskite/TiO2 interface. The comprehensive experiments demonstrate that ATFC can not only optimize the conductivity, electron mobility, and energy band structure of the TiO2 layer by passivation of the undercoordinated Ti4+, oxygen vacancy (VO), and free OH defects but also promote the yield of high‐quality CsPbI3 film by synergistic passivation of undercoordinated Pb2+ defects with the CO group and F atom, and limiting I− migration via F···I interaction. Benefiting from the above interactions, the ATFC‐modified CsPbI3 device yields a champion power conversion efficiency (PCE) of 21.11% and an excellent open‐circuit voltage (VOC) of 1.24 V. Meanwhile, the optimized CsPbI3 PSC maintains 92.74% of its initial efficiency after aging 800 h in air atmosphere, and has almost no efficiency attenuation after tracking at maximum power point for 350 h. [ABSTRACT FROM AUTHOR]

All‐inorganic CsPbX3 (X = I, Br, Cl or their mixtures) perovskites attract enormous attention in recent years due to their excellent optoelectronic properties, outstanding thermal/light stability, and wide range of applications in electronic devices. Encouragingly, the reported power conversion efficiency of CsPbX3 perovskite solar cells (PSCs) rockets up from 2.9% in 2015 to the present 21.0%. In order to further promote the performance of CsPbX3 PSCs toward the Shockley–Queisser efficiency limit, it is important to optimize the quality of perovskite films by crystallization kinetics modulation and defect suppression. In this review, first, some fundamental information about all‐inorganic CsPbX3 perovskites is briefly introduced, including the crystallization mechanism, growth mode, crystal structure, and phase stability as well as possible defects and their effects on device performance. Second, the recent exciting progress of the crystallization modulation strategies for high‐quality CsPbX3 films is summarized and discussed in detail. The advantages of different strategies, including annealing engineering, solvent engineering, precursor engineering, composition engineering, and interface engineering, are highlighted. Finally, methods for improving the efficiency of inorganic PSCs are discussed, and the future development prospects of inorganic PSCs are also outlined. [ABSTRACT FROM AUTHOR]

The improvement of power conversion efficiency (PCE) and stability of the perovskite solar cell (PSC) is hindered by carrier recombination originating from the defects at the buried interface of the PSC. It is crucial to suppress the nonradiative recombination and facilitate carrier transfer in PSC via interface engineering. Herein, P‐biguanylbenzoic acid hydrochloride (PBGH) is developed to modify the tin oxide (SnO2)/perovskite interface. The effects of PBGH on carrier transportation, perovskite growth, defect passivation, and PSC performance are systematically investigated. On the one hand, the PBGH can effectively passivate the trap states of Sn dangling bonds and O vacancies on the SnO2 surface via Lewis acid/base coordination, which is conducive to improving the conductivity of SnO2 film and accelerating the electron extraction. On the other hand, PBGH modification assists the formation of high‐quality perovskite film with low defect density due to its strong interaction with PbI2. Consequently, the PBGH‐modified PSC exhibits a champion power conversion efficiency (PCE) of 24.79%, which is one of the highest PCEs among all the FACsPbI3‐based PSCs reported to date. In addition, the stabilities of perovskite films and devices under high temperature/humidity and light illumination conditions are also systematically studied. [ABSTRACT FROM AUTHOR]

Surmounting complicated defects at the electron transport layer (ETL) and perovskite interface plays a non‐trivial role in improving efficiency and stability of perovskite solar cells (PSCs). Herein, an asymmetric interface modification strategy (AIMS) is developed to passivate the defects from both a SnO2 ETL and the perovskite buried surface via incorporating 1,3‐thiazole‐2,4‐diammonium (TDA) into the SnO2/perovskite interface. Detailed experimental and calculated results demonstrate that N3 (the nitrogen atom bonding to the imine) in the TDA preferentially cures the free hydroxyl (OH), oxygen vacancy (VO), and the Sn‐related defects on the SnO2 surface, while N1 (the nitrogen atom bonding to the vinyl) is more inclined to passivate the Pb2+ and I− related defects at the perovskite buried surface. As a result, the TDA‐modified FACsPbI3 PSC yields a champion power conversion efficiency (PCE) of 24.96% with a gratifying open‐circuit voltage (Voc) of 1.20 V. In addition, the optimized PSCs exhibit charming air‐operational stability with the unencapsulated device sustaining 97.04% of its initial PCE after storage in air conditions for 1400 h. The encapsulated device maintains 90.21% of its initial PCE after maximum power point tracking for 500 h. [ABSTRACT FROM AUTHOR]

High density of defects at interface severely affects the performance of perovskite solar cells (PSCs). Herein, cobalt (II) hexafluoro‐2,4‐pentanedionat (CoFAc), a hinge‐type fluorine‐rich complex, is introduced onto the surface of formamidinium cesium lead iodide (FACsPbI3) film to address the issues of perovskite/Spiro‐OMeTAD interface. The existence of CoFAc passivates both organic cation and halide anion vacancies by establishing powerful hydrogen bonds with HC(NH2)2+ (FA+) and strong ionic bonds with Pb2+ in perovskite films. In addition, CoFAc serves as a connecting link to enhance interfacial hole‐transport kinetics via interacting with Spiro‐OMeTAD. Consequently, FACsPbI3 PSCs with CoFAc modification display a champion power conversion efficiency (PCE) of 24.64% with a charming open‐circuit voltage (VOC) of 1.191 V, which is the record VOC among all the reported organic‐inorganic hybrid PSCs with TiO2 as electron transport layer. Furthermore, CoFAc‐modified devices exhibit an outstanding long‐term stability, which can maintain 95% of their initial PCEs after exposure to ambient atmosphere for 1500 h without any encapsulation. [ABSTRACT FROM AUTHOR]

All‐inorganic CsPbI3 perovskite presents preeminent chemical stability and a desirable band gap as the front absorber for perovskite/silicon tandem solar cells. Unfortunately, CsPbI3 perovskite solar cells (PSCs) still show low efficiency due to high density of defects in solution‐prepared CsPbI3 films. Herein, three kinds of hydrazide derivatives (benzoyl hydrazine (BH), formohydrazide (FH) and benzamide (BA)) are designed to reduce the defect density and stabilize the phase of CsPbI3. Calculation and characterization results corroborate that the carboxyl and hydrazine groups in BH form strong chemical bonds with Pb2+ ions, resulting in synergetic double coordination. In addition, the hydrazine group in the BH also forms a hydrogen bond with iodine to assist the coordination. Consequently, a high efficiency of 20.47 % is achieved, which is the highest PCE among all pure CsPbI3‐based PSCs reported to date. In addition, an unencapsulated device showed excellent stability in ambient air. [ABSTRACT FROM AUTHOR]

Formamidinium methylammonium lead iodide (FAMAPbI3) perovskite has been intensively investigated as a potential photovoltaic material because it has higher phase stability than its pure FAPbI3 perovskite counterpart. However, its power conversion efficiency (PCE) is significantly inferior due to its high density of surface detects and mismatched energy level with electrodes. Herein, a bifunctional passivator, methyl haloacetate (methyl chloroacetate, (MClA), methyl bromoacetate (MBrA)), is designed to reduce defect density, to tune the energy levels and to improve interfacial charge extraction in the FAMAPbI3 perovskite cell by synergistic passivation of both CO groups and halogen anions. As predicted by modeling undercoordinated Pb2+, the MBrA shows a very strong interaction with Pb2+ by forming a dimer complex ([C6H10Br2O4Pb]2+), which effectively reduces the defect density of the perovskite and suppresses non‐radiative recombination. Meanwhile, the Br− in MBrA passivates iodine‐deficient defects. Consequently, the MBrA‐modified device presents an excellent PCE of 24.29%, an open‐circuit voltage (Voc) of 1.18 V (Voc loss ≈ 0.38 V), which is one of the highest PCEs among all FAMAPbI3‐based perovskite solar cells reported to date. Furthermore, the MBrA‐modified devices without any encapsulation exhibit remarkable long‐term stability with only 9% of PCE loss after exposure to ambient air for 1440 h. [ABSTRACT FROM AUTHOR]

Inorganic CsPbI2Br perovskite is promising for solar cell applications due to its excellent thermal stability and optoelectronic characteristics. Unfortunately, the current high‐efficiency CsPbI2Br perovskite solar cells (PSCs) are mostly fabricated in an inert atmosphere due to their instability to moisture. Herein, a low‐dimensional intermediate‐assisted growth (LDIAG) method is reported for the deposition of CsPbI2Br film in ambient atmosphere by introducing imidazole halide (IMX: IMI and IMBr) into the precursor solution to control both nucleation and growth kinetics. The IMX first combines with PbI2 in the precursor film to form a 2D intermediate which then gradually releases PbI2 to slowly form high‐quality CsPbI2Br film during annealing. It is found that the LDIAG method produces a uniform, highly crystalline, pinhole‐free, and stable CsPbI2Br film with low defect density. Consequently, the solar cell efficiency is increased to as high as 17.26%, one of the highest for this type of device. Furthermore, the bare device without any encapsulation shows excellent long‐term stability with ≈86% of its initial efficiency retained after being exposed to the ambient environment for 1000 h. This work provides a perspective to tune the intermediate phases and crystallization pathway for high‐performance inorganic PSCs formed under ambient conditions. [ABSTRACT FROM AUTHOR]

All‐inorganic CsPbI3 perovskite presents preeminent chemical stability and a desirable band gap as the front absorber for perovskite/silicon tandem solar cells. Unfortunately, CsPbI3 perovskite solar cells (PSCs) still show low efficiency due to high density of defects in solution‐prepared CsPbI3 films. Herein, three kinds of hydrazide derivatives (benzoyl hydrazine (BH), formohydrazide (FH) and benzamide (BA)) are designed to reduce the defect density and stabilize the phase of CsPbI3. Calculation and characterization results corroborate that the carboxyl and hydrazine groups in BH form strong chemical bonds with Pb2+ ions, resulting in synergetic double coordination. In addition, the hydrazine group in the BH also forms a hydrogen bond with iodine to assist the coordination. Consequently, a high efficiency of 20.47 % is achieved, which is the highest PCE among all pure CsPbI3‐based PSCs reported to date. In addition, an unencapsulated device showed excellent stability in ambient air. [ABSTRACT FROM AUTHOR]