Branched Fluorenylidene Derivatives with Low Ionization Potentials as Hole-Transporting Materials for Perovskite Solar Cells
Aistė Jegorovė, Jianxing Xia, Matas Steponaitis, Marytė Daškevičienė, Vygintas Jankauskas, Alytis Gruodis, Egidijus Kamarauskas, Tadas Malinauskas, Kasparas Rakštys, Khalid A. Alamry, Vytautas Getautis, Mohammad Khaja Nazeeruddin
Abstract
High Resolution Image Download MS PowerPoint Slide A group of small-molecule hole-transporting materials (HTMs) that are based on fluorenylidene fragments were synthesized and tested in perovskite solar cells (PSCs). The investigated compounds were synthesized by a facile two-step synthesis, and their properties were measured using thermoanalytical, optoelectronic, and photovoltaic methods. The champion PSC device that was doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) reached a power conversion efficiency of 22.83%. The longevity of the PSC device with the best performing HTM, V1387, was evaluated in different conditions and compared to that of 2,2′,7,7′-tetrakis( N,N -di- p -methoxyphenylamine)-9,9′-spirobifluorene (spiro-MeOTAD), showing improved stability. This work provides an alternative HTM strategy for fabricating efficient and stable PSCs.