Facile synthesis of 'lucky clover' hole-transport material for efficient and stable large-area perovskite solar cells

Hole-transporting materials (HTMs) play a vital role of transporting holes from the perovskite layer to the counter electrode in perovskite solar cells (PSCs). A novel HTM BTPA-8 is feasibly synthesized by incorporating four dimethoxytriphenylamine leaflets and anthracene-based central bridge. BTPA-8 exhibits a suitable band alignment with MAPbI3 (MA = CH3NH3) or FA0.85MA0.15PbI3 (FA=HC(NH2)2), high hole mobility, and high thermal stability. The best FA0.85MA0.15PbI3 device based on BTPA-8 exhibits a power conversion efficiency (PCE) of 17.99% in the reverse scan with an aperture area of 0.09 cm2. Under the same condition, a PCE of 18.92% is achieved by the solar cell based on the standard spiro-OMeTAD (2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene). A comparable PCE of 12.31% is also obtained for BTPA-8 based MAPbI3 device compared with spiro-OMeTAD (13.25%) with an aperture area >1 cm2. BTPA-8 based PSCs exhibit better long-term stability than spiro-OMeTAD due to its high hydrophobicity. A lower synthesis cost of BTPA-8 than that of spiro-OMeTAD along with the elevated long-term stability makes it promising for application in PSCs.