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All‐polymer solar cells have experienced rapid development in recent years by the emergence of polymerized small molecular acceptors (PSMAs). However, the strong chain entanglements of polymer donors (PDs) and polymer acceptors (PAs) decrease the miscibility of the resulting polymer mixtures, making it challenging to optimize the blend morphology. Herein, we designed three PAs, namely PBTPICm‐BDD, PBTPICγ‐BDD and PBTPICF‐BDD, by smartly using a BDD unit as the polymerized unit to copolymerize with different Y‐typed non‐fullerene small molecular acceptors (NF‐SMAs), thus achieving a certain degree of distortion and giving the polymer system enough internal space to reduce the entanglements of the polymer chains. Such effects increase the chances of the PD being interspersed into the acceptor material, which improve the solubility between the PD and PA. The PBTPICγ‐BDD and PBTPICF‐BDD displayed better miscibility with PBQx‐TCl, leading to a well optimized morphology. As a result, high power conversion efficiencies (PCEs) of 17.50 % and 17.17 % were achieved for PBQx‐TCl : PBTPICγ‐BDD and PBQx‐TCl : PBTPICF‐BDD devices, respectively. With the addition of PYFT‐o as the third component into PBQx‐TCl : PBTPICγ‐BDD blend to further extend the absorption spectral coverage and finely tune microstructures of the blend morphology, a remarkable PCE of 18.64 % was realized finally. [ABSTRACT FROM AUTHOR]

Organic self‐assembled molecules (OSAMs) based hole‐transporting materials play a pivotal role in achieving highly efficient and stable inverted perovskite solar cells (IPSCs). However, the reported carbazol‐based OSAMs have serious drawbacks, such as poor wettability for perovskite solution spreading due to the nonpolar surface, worse matched energy arrangement with perovskite, and limited molecular species, which greatly limit the device performance. To address above problems, a novel OSAM [4‐(3,6‐glycol monomethyl ether‐9H‐carbazol‐9‐yl) butyl]phosphonic acid (GM‐4PACz) was synthesized as hole‐transporting material by introducing glycol monomethyl ether (GM) side chains at carbazolyl unit. GM groups enhance the surface energy of Indium Tin Oxide (ITO)/SAM substrate to facilitate the nucleation and growth of up perovskite film, suppress cation defects, release the residual stress at SAM/perovskite interface, and evaluate energy level for matching with perovskite. Consequently, the GM‐4PACz based IPSC achieves a champion PCE of 25.52 %, a respectable open‐circuit voltage (VOC) of 1.21 V, a high stability, possessing 93.29 % and 91.75 % of their initial efficiency after aging in air for 2000 h or tracking at maximum power point for 1000 h, respectively. [ABSTRACT FROM AUTHOR]

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]

Volatile solid additives have attracted increasing attention in optimizing the morphology and improving the performance of currently dominated non‐fullerene acceptor‐based organic solar cells (OSCs). However, the underlying principles governing the rational design of volatile solid additives remain elusive. Herein, a series of efficient volatile solid additives are successfully developed by the crossbreeding effect of chalcogenation and iodination for optimizing the morphology and improving the photovoltaic performances of OSCs. Five benzene derivatives of 1,4‐dimethoxybenzene (DOB), 1‐iodo‐4‐methoxybenzene (OIB), 1‐iodo‐4‐methylthiobenzene (SIB), 1,4‐dimethylthiobenzene (DSB) and 1,4‐diiodobenzene (DIB) are systematically studied, where the widely used DIB is used as the reference. The effect of chalcogenation and iodination on the overall property is comprehensively investigated, which indicates that the versatile functional groups provided various types of noncovalent interactions with the host materials for modulating the morphology. Among them, SIB with the combination of sulphuration and iodination enabled more appropriate interactions with the host blend, giving rise to a highly ordered molecular packing and more favorable morphology. As a result, the binary OSCs based on PM6:L8‐BO and PBTz‐F:L8‐BO as well as the ternary OSCs based on PBTz‐F:PM6:L8‐BO achieved impressive high PCEs of 18.87%, 18.81% and 19.68%, respectively, which are among the highest values for OSCs. [ABSTRACT FROM AUTHOR]

A double‐fibril network of the photoactive layer morphology is recognized as an ideal structure facilitating exciton diffusion and charge carrier transport for high‐performance organic solar cells (OSCs). However, in the layer‐by‐layer processed OSCs (LbL‐OSCs), polymer donors and small molecule acceptors (SMAs) are separately deposited, and it is challenging to realize a fibril network of pure SMAs with the absence of tight interchain entanglement as polymers. In this work, crystalline small molecule donors (SMDs), named TDZ‐3TR and SeDZ‐3TR, were designed and introduced into the L8‐BO acceptor solution, forcing the phase separation and molecular fibrilization. SeDZ‐3TR showed higher crystallinity and lower miscibility with L8‐BO acceptor than TDZ‐3TR, enabling more driving force to favor the phase separation and better molecular fibrilization of L8‐BO. On the other hand, two donor polymers of PM6 and D18 with different fibril widths and lengths were put together to optimize the fibril network of the donor layer. The simultaneously optimization of the acceptor and donor layers resulted in a more ideal double‐fibril network of the photoactive layer and an impressive power conversion efficiency (PCE) of 19.38 % in LbL‐OSCs. [ABSTRACT FROM AUTHOR]

As simple and versatile tools, additives have been widely used to refine active layer morphology and have played a crucial role in boosting the power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, three novel solvent additives named Th‐FSi, Th‐ClSi, and Th‐BrSi with the same backbone of 2,5‐bis(trimethylsilyl)thiophene are designed and synthesized by substituting different halogens of fluorine, chlorine, and bromine, respectively. Notably, Th‐ClSi exhibits the more significant dipole moment and engages in non‐covalent interactions with a small‐molecule acceptor (SMA) L8‐BO, which slight adjustments in intermolecular interaction, crystallinity, and molecular packing in the PM6:L8‐BO active layer. Consequently, the OSCs incorporating Th‐ClSi outperform their Th‐FSi and Th‐BrSi counterparts in photo‐capturing, reduced energy loss, superior exciton dissociation, and charge transfer properties, out‐coming yields in an enhanced PCE of 18.29%. Moreover, by integrating a near‐infrared absorbing SMA (BTP‐eC9) guest into the PM6:L8‐BO matrix, the absorption spectrum to span 880–930 nm, and the resultant ternary OSCs achieve a commendable PCE of 19.17%, ranking among the highest efficiencies reported to date is expanded. These findings underscore the promise of halogenated thiophene‐based solvent additives as a potent avenue for morphological fine‐tuning and consequent PCE enhancement in OSCs. [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]

Highlights: Alkyl-tailored Y-SMAs named YR-SeNF series with near-infrared absorption, different molecular crystallinity and self-assembly abilities are developed. The related organic solar cells (OSCs) with an active layer processed from halogen-free solvents and spin-coating-free technologies achieve a ~ 19% efficiency. Ternary OSCs offer a robust operating stability under MPP tracking and well-keep > 80% of the initial efficiency for even over 400 h. Power-conversion-efficiencies (PCEs) of organic solar cells (OSCs) in laboratory, normally processed by spin-coating technology with toxic halogenated solvents, have reached over 19%. However, there is usually a marked PCE drop when the blade-coating and/or green-solvents toward large-scale printing are used instead, which hampers the practical development of OSCs. Here, a new series of N-alkyl-tailored small molecule acceptors named YR-SeNF with a same molecular main backbone are developed by combining selenium-fused central-core and naphthalene-fused end-group. Thanks to the N-alkyl engineering, NIR-absorbing YR-SeNF series show different crystallinity, packing patterns, and miscibility with polymeric donor. The studies exhibit that the molecular packing, crystallinity, and vertical distribution of active layer morphologies are well optimized by introducing newly designed guest acceptor associated with tailored N-alkyl chains, providing the improved charge transfer dynamics and stability for the PM6:L8-BO:YR-SeNF-based OSCs. As a result, a record-high PCE approaching 19% is achieved in the blade-coating OSCs fabricated from a green-solvent o-xylene with high-boiling point. Notably, ternary OSCs offer robust operating stability under maximum-power-point tracking and well-keep > 80% of the initial PCEs for even over 400 h. Our alkyl-tailored guest acceptor strategy provides a unique approach to develop green-solvent and blade-coating processed high-efficiency and operating stable OSCs, which paves a way for industrial development. [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]

Highlights: Wide-bandgap perovskite solar cells are reviewed in detail from the views of compositions, additives, charge transport layers, interfaces and preparation methods. The key factors affecting open-circuit voltage and photostability are carefully discussed. The future directions and challenges in developing wide-bandgap perovskite solar cells are highlighted. Perovskite-based tandem solar cells have attracted increasing interest because of its great potential to surpass the Shockley–Queisser limit set for single-junction solar cells. In the tandem architectures, the wide-bandgap (WBG) perovskites act as the front absorber to offer higher open-circuit voltage (VOC) for reduced thermalization losses. Taking advantage of tunable bandgap of the perovskite materials, the WBG perovskites can be easily obtained by substituting halide iodine with bromine, and substituting organic ions FA and MA with Cs. To date, the most concerned issues for the WBG perovskite solar cells (PSCs) are huge VOC deficit and severe photo-induced phase separation. Reducing VOC loss and improving photostability of the WBG PSCs are crucial for further efficiency breakthrough. Recently, scientists have made great efforts to overcome these key issues with tremendous progresses. In this review, we first summarize the recent progress of WBG perovskites from the aspects of compositions, additives, charge transport layers, interfaces and preparation methods. The key factors affecting efficiency and stability are then carefully discussed, which would provide decent guidance to develop highly efficient and stable WBG PSCs for tandem application. [ABSTRACT FROM AUTHOR]

A desired morphology is essential for achieving efficient polymer solar cells. Donors and acceptors with appropriate crystallization can lead to a suitable phase-separated morphology for effective photocurrent generation process. Inspired by the success of Y6 acceptors and the 2D side chain engineering on popular polymer donors and small molecule acceptors, the usage of unique 2D 3,4-ethylene dioxythiophene (EDOT) side chains on Y6 to regulate its crystallinity, compatibility, and thus the related blend morphology is explored. In this study, two molecules of BTP-EDOT-4F and BTP-EDOT-4Cl with such unique 2D EDOT side chains are designed and synthesized. Due to the advantage of EDOT side chain, when these molecules are blended with PM6, the decent power conversion efficiencies (PCEs) of 16.78% and 15.87% are obtained. Furthermore, BTP-EDOT-4F is selected as the third component and added into PM6:L8-BO binary system to form ternary blends. The optimized crystallinity, compatibility, and morphology of such ternary blend are discovered in the presence of BTP-EDOT-4F, which enables efficient exciton dissociation and charge transport as well as decreased recombination, resulting in higher short circuit current density Jsc) and fill factor. Finally, the outstanding PCE of 18.56% is achieved in ternary blends containing PM6, L8-BO, and BTP-EDOT-4F. [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]

Constructing terpolymer has attracted increasing attention as a strategy to improve the performance of polymer solar cell. Terpolymer usually offers an opportunity to lower the frontier molecular orbital energy level, introduces additional absorption band and sometimes optimizes the morphology of the active blend. Generally, the additional segment in terpolymer backbone inevitably introduces backbone disorder, which causes entropy rises. However, selecting a suitable dipole unit introduces extra driving forces for crystallization by enhancing intermolecular interactions. This provides a handy knob for tradeoff between intermolecular interaction and backbone disorder, thus regulating the blend morphology. Herein, a high dipole and electron‐deficient group of pyrrolo[3,4‐f]benzotriazole‐5,7(6H)‐dione (TzBI) is incorporated into the high‐performance donor polymer and a series of terpolymers with different content of TzBI are designed. As expected, the morphology is optimized gradually for improving charge generation and charge transport, also suppressing charge recombination. The champion device with 10% TzBI exhibited a power conversion efficiency (PCE) of 18.36%, which is 5% increase compared to the controlled device. This study presents a charming terpolymer strategy by highly electron‐deficient and high dipole segment to realize a tradeoff between intermolecular interaction and backbone disorder, facilitating the optimization of morphology and elevation of fill factor and device efficiency. [ABSTRACT FROM AUTHOR]

Side‐chain engineering with heteroatoms is not only effective in tuning frontier molecular orbitals, but also possible for forming secondary bonds which can be utilized to planarize the molecular backbone, hence, improving the photon absorption as well as charge‐transport abilities of polymer solar‐cell (PSC) materials. Herein, two types of unconventional side chains, namely carboxylate and carbamate, containing various heteroatoms are introduced to the thiophene bridges in high performance benzodithiophene (BDT) based donor polymers to from the novel polymers PTzTz‐C and PTzTz‐N, respectively. In these polymers, non‐covalent O⋅⋅⋅S and N⋅⋅⋅H interactions induce a high tendency to aggregation. In a ternary‐blend PSC with PTzTz‐N added to the high‐performance D18 : BTP‐eC9 blend, complimentary absorption and improved thin‐film morphology were observed with a top power conversion efficiency of 18.76 %, which is an improvement of almost 5 % over the D18 : BTP‐eC9 binary blends. [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]

The ternary copolymerization strategy has emerged as a promising strategy for developing high‐efficiency donor polymers in polymer solar cells (PSCs). Terpolymers based on the star polymer PM6 have already realized good photovoltaic performance. However, challenges such as the intricate synthesis of fluorine‐substituted benzodithiophene (F‐BDT) unit of PM6 and entropy increase induced by backbone disorder have hindered the construction of high‐performance donor terpolymers. In this work, these challenges are addressed by opting for the cost‐effective chlorinated‐substituted benzodithiophene unit (Cl‐BDT) as an alternative to F‐BDT and incorporating the large dipole moment and electron‐deficient TPD group as the third component into the high‐performance donor polymer of PM7. As expected, this approach effectively suppresses terpolymer backbone disorder while enhancing crystallinity, thereby optimizing morphology and improving charge generation and transport. Remarkably, the PM7‐TPD‐10‐based device with 10% TPD replacement achieves a champion power conversion efficiency (PCE) of 18.26%. After introducing PM7‐TPD‐10 as the third component into D18:L8‐BO blend, a dual mechanism for improving the efficiency to 19.40% is realized. This work demonstrates that the high dipole moiety as the third component to construct terpolymers is an important strategy to suppress the backbone disorder and increase the crystallinity, facilitating the optimization of morphology and device performance. [ABSTRACT FROM AUTHOR]

This communication reports the synthesis of two novel chalcogen-atom-annulated perylene diimide (PDI) trimers with twisted structures, TriPDI-S and TriPDI-Se, for efficient nonfullerene polymer solar cells. TriPDI-Se exhibits more compact molecular arrangement due to the stronger intermolecular interactions induced by the selenium atom. This selenium annulation endows TriPDI-Se with improved absorption and crystallinity in its blend film. The resulting devices exhibit enhanced Jsc of 17.15 mA cm−2 and fill factor (FF) of 66.8%, which are much higher than those of TriPDI-S devices ( Jsc = 16.71 mA cm−2; FF = 63.6%). Although TriPDI-Se exhibits lower-lying energy levels, TriPDI-Se devices still obtain a higher Voc of 0.77 V compared to TriPDI-S devices ( Voc = 0.74 V), which is mainly originated from the reduced recombination in the related devices. Finally, the power conversion efficiency is significantly elevated from 7.86% for TriPDI-S devices to 8.82% for TriPDI-Se devices. [ABSTRACT FROM AUTHOR]

The molecular planarity of a small molecule donor is one of the key factors affecting its molecular packing behavior, the morphology of the related active blend and thus the photovoltaic properties of all small molecule organic solar cells (ASM-OSCs). In this contribution, a series of new benzodithiophene (BDT)-based A-π-D-π-A type small molecules were developed, namely SD1, SD2 and SD3, by combining the chemical modification of side chain (sulfuration), π-bridge (alkoxy groups introducing) and end group (different type or different alkyl chain). The sulfuration of the BDT side chains and introducing alkoxy group to the π-bridge could induce intermolecular S⋯S and intramolecular S⋯O non-covalent interactions for higher planarity of these small molecules. The rhodanine and cyanoacetate end groups showed less effect on the optical and electronic properties but significantly affected the molecular packing behavior and blend morphology. From SD1:Y6-T to SD2:Y6-T and SD3:Y6-T, the face-to-face packing was gradually reduced, while the face-to-edge packing was increased, which resulted in lowered exciton dissociation efficiency, further decreased the device performance. SD1:Y6-T blend exhibited more favorable face-to-face packing and ideal morphology for efficient charge dissociation and transport, contributing to a champion PCE of 10.12%. This work provided a deep insight of the donor and acceptor packing behavior effect on the photovoltaic property by molecular design. [Display omitted] [ABSTRACT FROM AUTHOR]

Y-type non-fullerene acceptors with outer bulky branched side chains and weaker electron withdrawing end groups were designed for polymer solar cells. A decent PCE of 15.03% was achieved for D18:BTP-TCl binary device, which was further improved to 19.15% by adding BTP-TCl to the D18:BTP-eC9 host blend. [Display omitted] • Y-typed small molecular acceptors were synthesized with upshifted LUMO levels. • D18:BTP-TCl achieved a decent PCE of 15.03 % with a high V oc of 0.986 V. • The ternary device of D18:BTP-eC9:BTP-TCl achieved a champion PCE of 19.15%. • Simultaneous enhancement of J sc and V oc of PSCs was achieved. Simultaneously enhancing the short-circuit current density (J sc) and open-circuit voltage (V oc) of current state-of-the-art polymer solar cells (PSCs) containing wide bandgap polymers as donors and Y6 derivatives as acceptors is of great challenge but essential for further improvement of the photovoltaic performances. In this work, two Y-type non-fullerene acceptors of BTP-T and BTP-TCl were designed and successfully synthesized with relatively weak electron-accepting thiophene based end groups, where blue-shifted absorption and upshifted LUMO energy levels were achieved to fill the well-known absorption gap at 700 nm of typical binary devices based Y-type molecules and rise the output voltage, respectively. Simultaneously increased J sc and V oc were achieved in ternary blend devices containing D18:BTP-eC9:BTP-TCl with a significantly improved PCE up to 19.15 %, which is over 7 % increase compared to the binary device. Our results illustrated the great potential of rational design of Y6 derivatives for constructing ternary PSCs to improve their performances. [ABSTRACT FROM AUTHOR]

A benzodithiophene-free donor polymer was designed for enabling 19.36% efficiency green-solvent-processable organic solar cells (OSCs), which is the highest value for OSCs processed by halogen-free solvents. [Display omitted] • A high molecular weight benzodithiophene-free donor polymer of PDTP-BDD was developed for organic solar cells. • The layer-by-layer processing of PDTP-BDD based devices in halogen-free solvents was studied. • The champion power conversion efficiency of 19.36% was achieved finally. In this work, a newly benzodithiophene-free D-A polymer donor, named PDTP-BDD, was developed for realizing green-solvent processed high-performance OSCs. By bridging two electron-rich unit of dithieno[3,2-b:2′,3′-d]pyridin-5(4H)-one (DTP) and electron-deficient benzo[1,2-c:4,5c′]dithiophene-4,8-dione (BDD) with thiophene units, PDTP-BDD possesses high absorption in the short wavelength range and a deep HOMO energy level. The rigid building blocks also make PDTP-BDD has strong aggregation and poor solubility in common halogen-free solvents (such as o -xylene) at room temperature, but it is readily dissolved and disaggregated at high temperature (120 °C). After cooling down to a lower temperature (60 °C), PDTP-BDD self-assembled and pre-aggregated slowly in the solution at a long time. By employing a delayed processing strategy in the layer-by-layer processed OSCs (LbL-OSCs), an optimized fibril network of the underling layer was realized, enabling the permeation of acceptor into the donor network. The optimized PDTP-BDD/L8-BO-based LbL-OSCs realized a high PCE of 18.42 %. By adding a small amount of D18 to further optimize the PDTP-BDD fibril network, an impressive PCE of 19.36 % was achieved finally in the resulting ternary LbL-OSCs, which is the highest value for OSCs processed by halogen-free solvents. [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]

The chalcogen effect was investigated on the absorption, energy level and intermolecular interaction of nonfused-ring electron acceptors, which presented TTS-4F containing sulfur substituted side chains to achieve a champion PCE of 14.74% in organic solar cells. [Display omitted] • Nonfused-ring electron acceptors (NFREAs) based on chalcogen substituted side chains were developed. • The chalcogen effect on the photovoltaic property of NFREAs was investigated. • The champion power conversion efficiency 14.74% was achieved finally. Fused-ring electron acceptors (FREAs) are the current working horse for the top performing organic solar cells (OSCs). Nevertheless, these FREAs surfer from high synthetic complexity, production costs and poor scalability, hindering their industrialization. Developing nonfused-ring electron acceptors (NFREAs) is a more feasible alternative solution towards future photovoltaic applications. In this work, a series of NFREAs have been designed and synthesized by introducing chalcogen atoms on the side chains for OSCs. The introduced chalcogen atoms (O, S, and Se) not only modulated the energy levels but also finely tuned the intermolecular interactions. Especially, the formed S‧‧‧S and Se‧‧‧Se intermolecular interactions in TTS-4F and TTSe-4F resulted in higher molecular crystallinity than TTO-4F. Unexpectedly, the strong Se‧‧‧Se interactions also led the aggregation of TTSe-4F and formation of large domains in the PM6:TTSe-4F blend. The moderate S‧‧‧S interactions in TTS-4F enabled an optimal phase separation with more ideal nano fibrils distributed in the PM6:TTS-4F blend, facilitating the charge separation and transport. As a result, TTS-4F based devices achieved a champion power conversion efficiency (PCE) of 14.74%, higher than the TTO-4F (8.76%) and TTSe-4F (11.56%) based devices. [ABSTRACT FROM AUTHOR]