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Hole transport materials (HTMs) are essential for improving the stability and efficiency of perovskite solar cells (PSCs). In this study, we have designed and synthesized a novel organic small molecule HTM, cor‐(DPA)5, characterized by a bowl‐shaped core with symmetric five diphenylamine groups. Compared to already‐known HTMs, the bowl‐shaped and relatively compact structure of cor‐(DPA)5 facilitates intermolecular π–π interactions, promotes film formations, and enhances charge transport. Consequently, the cor‐[DPA(2)]5 HTM exhibits high charge mobility, exceptional hydrophobicity, and a significantly elevated glass transition temperature. Superior to previously reported HTMs such as spiro‐OMeTAD and cor‐OMePTPA, our newly synthesized cor‐(DPA)5 HTM is free from any ionic dopants. As a result, the dopant‐free cor‐[DPA(2)]5‐based PSC demonstrates an impressive efficiency of 24.01 %, and exhibits outstanding operational stability. It retains 96 % after continuous exposure to 1 sun irradiation for 800 hours under MPP (maximum power point) tracking in ambient air. These findings present a structurally compact novel HTM and exemplify a new approach to the molecular design of HTM for the development of stable and effective PSCs. [ABSTRACT FROM AUTHOR]

Fullerene (C60) and its derivatives are the most prevalent and efficient electron transport materials (ETMs) for state‐of‐the‐art perovskite solar cells (PSCs). Benefiting from the high performance, simple synthesis, and easy availability of raw materials, fulleropyrrolidine derivatives (FDs) are potential next‐generation ETM alternatives to currently used fullerene materials. However, the power conversion efficiency (PCE) of FDs still lags far behind that of methanofullerene derivatives such as [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM). Moreover, the underlying mechanism remains unclear. In this work, six FD ETMs are designed and synthesized, i.e., CN‐TPAX (X = H, Me, OMe, Cl, Br, I), for p‐i‐n PSCs, and obtained a champion PCE of over 25% for the CN‐TPACl ETM, outperforming all reported FDs until now. Subsequently, their performance is systematically characterized in terms of molecular characteristics, including single‐crystal structure, electronic properties, film formability/morphology, and electron dynamics, which helped reveal the terminal effects of FD ETMs on the molecular characteristics and photovoltaic performance of PSCs. This approach clarified the structure–performance relationships between the FDs and the resulting devices, highlighting the importance of the terminal design of fullerene ETMs for high‐performance PSCs. [ABSTRACT FROM AUTHOR]

Three novel donor–acceptor–acceptor configured small molecules with benzotriazole as the central A building block are synthesized as donor materials for vacuum‐deposited small‐molecule organic solar cells (SMOSCs). The effects of different lengths of the side chains attached to the benzotriazole block on the molecular structure, electrochemical behavior, and optical properties of these donors are investigated systematically. Vacuum‐deposited SMOSCs fabricated with these small molecule donors and C70 as the acceptor exhibit power conversion efficiencies (PCEs) in the range of 6.42–7.43% under air mass 1.5 global (AM 1.5 G) 100 mW cm−2 simulated solar illumination. Furthermore, the Me‐DTDCPT‐based devices deliver a promising PCE of 14.84% under 600 lux illumination by a fluorescent lamp, demonstrating its potential in indoor photovoltaic applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Corannulene-cored molecules acted as novel HTMs for inverted PSCs. • Excellent molecular/film properties offered a remarkable hole-transporting process. • Cor-SMePTPA-based PSC achieved a highest PCE of 21.7% with an excellent stability. • The molecular/film effects on photovoltaic parameters of the device were elucidated. Hole transporting materials (HTMs), owing to their unique bottom position in inverted perovskite solar cells (PSCs), exert a considerable influence on the hole-transporting process and the morphology/performance of the perovskite layers. Considering the well-known interfacial problems associated with commonly-used NiO x and poly(triarylamine) HTMs in traditional inverted PSCs, there is an urgent need for exploring efficient HTMs exhibiting good film formability/processability and interfacial contact to meet the specific requirements of high-performance and stable inverted PSCs. Herein, we fabricated inverted PSCs involving two star-like, dopant-free, corannulene-cored HTMs with O-terminals (sym -penta(N, N -bis(4-methoxyphenyl)aniline)corannulene, namely Cor-OMePTPA) and S-terminals (sym -penta(N, N -bis(4-(methylthio)phenyl)aniline)corannulene, namely Cor-SMePTPA) for the first time. The Cor-SMePTPA HTM exhibited a stronger hole-transporting ability and a better interfacial chemical linkage when compared to the Cor-OMePTPA HTM. The device containing Cor-SMePTPA HTM delivered a power conversion efficiency of 21.70%, which was the highest among inverted PSCs based on methylthio (SMe)-terminated HTMs. Furthermore, comprehensive experimental and theoretical characterizations clearly showed that the core and outer terminals (O or S) affected the optoelectric and chemical properties of the HTMs as well as the photovoltaic performance and stability of the corresponding PSCs, highlighting the superiority of the design involving a corannulene core and SMe groups in HTMs for inverted PSCs. We believe that such dopant-free corannulene-cored HTMs can have considerable potential for realizing highly efficient and stable PSCs in the future. [ABSTRACT FROM AUTHOR]