Enhanced Photovoltaic Performance by Improved Hole Extraction with a Molecule Dopant in Inverted Perovskite Solar Cells

Although poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) has been widely applied in inverted perovskite solar cells, inherent poor conductivity and energy level mismatch seriously constrain development of the power conversion efficiency (PCE) of PTAA-based inverted perovskite solar cells. Herein, a high-hole-mobility small molecule alpha-6T is employed as a PTAA solution dopant for inverted perovskite solar cells to solve the above issues. alpha-6T significantly increases the conductivity and hole mobility of PTAA films and decreases the energy barrier at the PTAA/perovskite interface, leading to enhanced carrier extraction and suppressed recombination. Furthermore, the wettability of the PTAA film is also improved. As a result, the doped device shows a champion PCE of 22.23%, which is observably higher than 20.24% of the control device. What's more, the unencapsulated devices maintain similar to 80% of initial PCE after being stored under air conditions for 1500 h. This strategy provides a simple way to fabricate high-performance PTAA-based inverted perovskite solar cells.