Interfacial Defect Passivation Effect of N-Methyl-N-(thien-2-ylmethyl)amine for Highly Effective Perovskite Solar Cells

Lead ammonium halide hybrid perovskite solar cells (PSCs) are making unprecedented progress as a favorite in photovoltaic technology. However, nonradiative recombination losses caused by defects on the surface of perovskites impede their development. Thereby, it is very important to mitigate or passivate these defects in perovskite films. Herein, a simple defect passivation strategy was designed using N-methyl-N-(thien-2-ylmethyl)amine (NMTMA) as a passivator at the interface of the perovskite layer and the spiro-OMeTAD hole transport layer (HTL). The results show that the amine group and the thiophene group on the NMTMA can coordinate with the lead ions on the perovskite layer, which effectively reduces the trap-state density and nonradiative carrier recombination. Typically, 1 mg mL(-1) NMTMA-modified device achieves a power conversion efficiency (PCE) of 22.67%, together with improved environmental stability and hysteresis effect. This study provides a typical case for organic functional molecules to passivate defects in PSCs.