Novel Facilely Synthesized spiro[Fluorene-9,9′-phenanthren-10′-one] in D-A-D Hole-transporting Materials for Perovskite Solar Cells

This is the first report of donor-acceptor-donor (D-A-D) hole-transporting materials (HTMs) with spiro linkage in perovskite solar cells (PSCs). We demonstrated two novel D-A-D type HTMs with spiro[fluorene-9,9'-phenanthren-10'-one] as the core structure. Yih-series HTMs achieved low cost, high yield, and ease of operation. Yih-2 achieved slightly higher R_s, and R_sh, and hole mobility can enhance the performance of PSCs. Yih-2 exhibited higher Voc and. Z, than did Yih-l. We discuss the photovoltaic performance of PSCs. Consequently, Yih-2 as an HTM in PSCs achieved J_sc of 22.18 mA.cm^-2, V_oc of 1.02 V, and fill factor of 0.71, corresponding to an overall conversion efficiency of 16.06%, which was similar to that of spiro-OMeTAD (16.08%). The photophysical properties of HTMs were analyzed through time-dependent density functional theory with the B3LYP functional.