A facile strategy for high performance air-processed perovskite solar cells with dopant-free poly(3-hexylthiophene) hole transporter

Poly(3-hexylthiophene) (P3HT) based devices possess potential toward low-cost and easy fabrication for high-performance perovskite solar cells (PSCs). However, these devices currently suffer from stability and relative low performance. Herein, a gradient mixed-cation perovskite is obtained by a facile strategy of tailoring MAPbI 3-x Cl x , in which MAFAPbI 3-x Cl x were constructed in ambient air by directly spin-coating FAI onto perovskite intermediate phase. The pristine device shows an inferior power conversion efficiency (PCE) of 13.71%, whereas the as-optimized device achieves a PCE of 16.26%. A gradient distribution of FA cation is revealed by crystal unit parameters and energy dispersive spectrometer (EDS). The lifted valence band edge matches better with the HOMO of P3HT, thus resulting in the faster charge extraction. In addition, the reduced trap states lead to the enhanced crystallinity and the mitigation of perovskite/P3HT interface, and then the stability is significantly enhanced. Our work provides a facile way to improve the performance of P3HT based air-processed PSCs, which can bring these devices closer to low-cost commercial applications.