Quaternary ammonium halide-containing cellulose derivatives for defect passivation in MAPbI3-based perovskite solar cells†
In this study we synthesized quaternary ammonium halide-containing cellulose derivatives (PQ-Cl, PQ-Br, PQ-F) for use as defect passivation additives in methylammonium lead iodide (MAPbI3)-based inverted perovskite solar cells (PVSCs). The defect passivation efficiency of PQ-Cl was much better than those of PQ-F and PQ-Br. The addition of the PQ-Cl to the MAPbI3 layer repaired the crystal defects, increased the crystallinity, and improved the coverage of the perovskite layer during the formation of the resulting perovskite films. Accordingly, the UV-Vis absorption intensities and external quantum efficiencies of the PQ-Cl-doped perovskite films were enhanced, especially for the MAPbI3 film blended with 0.06 wt% of PQ-Cl. The photovoltaic (PV) performance and stability of the PQ-Cl-incorporated PVSCs were improved relative to those of the control sample. The architecture of the cellulose derivative-doped inverted PVSCs was indium tin oxide/P3CT-Na/cellulose derivative (PQ-F, PQ-Cl, or PQ-Br):MAPbI3/PC61BM/bathocuproine/Ag. The PV performance and stability of the PQ-Cl-incorporated PVSC were superior to those of the PQ-F- and PQ-Br-doped PVSCs. The PVSC incorporating 0.06 wt% of PQ-Cl displayed the best PV performance, with a power conversion efficiency (PCE) of 15.01%, an open-circuit voltage of 1.00 V, a short-circuit current density of 20.32 mA cm−1, and a fill factor of 76.80%. This PQ-Cl-0.06-based PVSC retained 92% of its initial PCE after 600 h of storage under ambient conditions (30 °C; 60% relative humidity).