Molecular Design and Cost-Effective Synthesis of Tetraphenylethene-Based Hole-Transporting Materials for Hybrid Solar Cell Application

The innovative choice of core and periphery groups for organic hole-transporting materials (HTMs) has gained more attention for modern development in hybrid organic–inorganic perovskite solar cells (PSCs). For large-scale application of PSCs, the replacement of 2,2′,7,7′-tetrakis(N,N-di-4-methoxyphenylamino)-9,9′-spirobifluorene (spiro-OMeTAD) has its demands such as low stability, high cost, and multistep synthesis. This has necessitated the introduction of novel cost-effective HTMs. Hence, at first, we obtained a theoretical design of tetraphenylethene (TPE)-based HTMs through the Gaussian method, which exhibits a substantial highest occupied molecular orbital energy level as compared with the perovskite. Further, the photophysical, electrochemical, and thermal properties were meticulously investigated with the aid of both experimental and computational methods. In order to enhance the solubility of HTMs in chlorobenzene, the methoxy-substituted phenyl group was replaced with the hexyloxy-substituted phenyl group, and also, the higher extent of solubility is recognized after the functional group exchanges. The power conversion efficiencies of TOHE and TOME are η = 13.96%, Jsc = 21.00 mA/cm2, and Voc = 0.93 (V) and η = 6.83%, Jsc = 13.45 mA/cm2, and Voc = 0.97 (V), respectively (under full sunlight AM 1.5G, 100 mW cm–2 irradiation). Moreover, the synthesis of highly stable TOHE involves a simple and cost-effective synthetic procedure, proving to be the most promising lead for designing efficient organic–inorganic hybrid solar cells.