Stable <scp>Methylammonium‐Free</scp> p‐i‐n Perovskite Solar Cells and <scp>Mini‐Modules</scp> with Phenothiazine Dimers as Hole‐Transporting Materials
Luigi Angelo Castriotta, Rossella Infantino, Luigi Vesce, Maurizio Stefanelli, Alessio Dessì, Carmen Coppola, Massimo Calamante, Gianna Reginato, Alessandro Mordini, Adalgisa Sinicropi, Aldo Di Carlo, Lorenzo Zani
Abstract
During the last decade, perovskite solar technologies underwent an impressive development, with power conversion efficiencies reaching 25.5% for single‐junction devices and 29.8% for Silicon‐Perovskite tandem configurations. Even though research mainly focused on improving the efficiency of perovskite photovoltaics (PV), stability and scalability remain fundamental aspects of a mature photovoltaics technology. For n‐i‐p structure perovskite solar cells, using poly‐triaryl(amine) (PTAA) as hole transport layer (HTL) allowed to achieve marked improvements in device stability compared with other common hole conductors. For p‐i‐n structure, poly‐triaryl(amine) is also routinely used as dopant‐free hole transport layer, but problems in perovskite film growth, and its limited resistance to stress and imperfect batch‐to‐batch reproducibility, hamper its use for device upscaling. Following previous computational investigations, in this work, we report the synthesis of two small‐molecule organic hole transport layers (BPT‐1,2), aiming to solve the above‐mentioned issues and allow upscale to the module level. By using BPT‐1 and methylammonium‐free perovskite, max. Power conversion efficiencies of 17.26% and 15.42% on a small area (0.09 cm 2 ) and mini‐module size (2.25 cm 2 ), respectively, were obtained, with a better reproducibility than with poly‐triaryl(amine). Moreover, BPT‐1 was demonstrated to yield more stable devices compared with poly‐triaryl(amine) under ISOS‐D1, T1, and L1 accelerated life‐test protocols, reaching maximum T 90 values >1000 h on all tests.