Constructing Molecular Bridge for High-Efficiency and Stable Perovskite Solar Cells based on P3HT Hole Transport Material

Abstract

Poly (3-hexylthiophene) (P3HT) is one of the most attracting hole transport materials (HTMs) for the pursuing of stable, low-cost and high-efficiency perovskite solar cells (PSCs). However, the poor contact and the severe recombination at P3HT/perovskite interface lead to a low power conversion efficiency (PCE). Thus, we have constructed a molecular bridge, MDN, whose malononitrile group can anchor the perovskite surface while triphenylamine group can form π − π stacking with P3HT, to form a charge transport channel. In addition, MDN was also found effectively passivate the defects and reduce the recombination to a large extent. Finally, a PCE of 22.87% has been achieved with MDN doped P3HT (M-P3HT) as HTM, much higher than the efficiency of PSCs with pristine P3HT. Furthermore, MDN gave the un-encapsulated device an enhanced long-term stability that 92% of its initial efficiency has been maintained even after two months of aging at 75% relative humidity (RH) followed by one month of aging at 85% RH in the atmosphere, and the PCE has not been changed after operating at the maximum power point (MPP) under 1 sun illumination (~ 45 oC in N2) over 500 hours.