Publication
The designed hole-transporting materials (HTMs) of asymmetric and symmetric benzoselenadiazole based molecules, referred as RSe-CF, RSe-TPA, and RSe-R, were synthesized and employed for improving the charge conduction and performance of mixed-halide (Cs(0.03)FA(0.97)PbI(2.9)Br(0.)(1)) perovskite solar cells (PSCs). In this work, the effects of different acceptor/donor units like 3,5-bis(trifluoromethyl) benzene (CF), alkyl thiophene (R), and triphenylamine (TPA) in benzoselenadiazole were investigated and their optoelectronic, structural, thermal, and photovoltaic properties were studied. The optical and electrochemical results of RSe-CF, RSe-TPA, and RSe-R exhibited the alternation of the energy levels for efficient interfacial charge transfer with mixed-halide Cs(0.03)FA(0.97)PbI(2.9)Br(0.)(1). RSe-TPA HTM-based PSCs displayed the highest power conversion efficiency (PCE) of similar to 17.3%, whereas PSCs based on RSe-CF and RSe-R HTMs displayed low PCEs of similar to 12.4% and similar to 15.9%, respectively. The PCE with a new RSe-TPA HTM is comparable to the PCE of the state-of-the-art HTM Spiro-OMeTAD. Observation of large quenching in photoluminescence spectra of the HTM/Cs(0.03)FA(0.97)PbI(2.9)Br(0.)(1) thin film supported the effective hole injection from perovskite's valence band to HOMO of HTMs, resulting in high PCE and high photocurrent density.
Mohammad Khaja Nazeeruddin, Yong Ding, Olga Syzgantseva, Xianfu Zhang, Cheng Liu