Multilayer Cascade Charge Transport Layer for High- Performance Inverted Mesoscopic All-Inorganic and Hybrid Wide-Bandgap Perovskite Solar Cells

摘要

It is imperative to improve the quality of light absorber and reduce the charge-carrier recombination for efficient perovskite solar cells (PSCs). Herein, a synergistic regulation strategy that combines the tailoring of crystallinity and construction of multilayer cascade charge transport layers (CTLs) for inverted CsPbI_2Br solar cells is presented. The film quality of CsPbI_2Br is well tuned via F~- doping. In addition, gradient energy alignment between perovskite and CTLs, i.e., NiO_x/Zn:CuGaO_2/perovskite and perovskite/TiO_2/PC_(61)BM/ZnO, favors the charge transfer and depresses carrier recombination. Noticeably, the TiO_2 interlayer with deep valence band maximum effectively blocks the hole backtransfer from perovskite to PC_(61)BM. These unique characteristics of the novel structured CsPbI_2Br device give a champion power conversion efficiency (PCE) of 15.10% along with good thermal and operational stability. Moreover, the graded CTLs can be expanded to methylammonium-free hybrid perovskite device (Eg=≈1.76 eV) by delivering a PCE of 18.12%, showing great promise in tandem solar cells for use as top cell.