Carbon-Based Electrode Engineering Boosts the Efficiency of All Low-Temperature-Processed Perovskite Solar Cells

Carbon electrode-based perovskite solar cells (PSCs) with low-cost and long-term stability have been recognized as a competitive candidate toward future practical applications. However, energy level mismatch and ineffective hole extraction at the carbon electrode/perovskite interface limit device performance. Herein, we develop a low-cost carbon-based electrode that utilizes a cheap small-molecule semiconductor copper phthalocyanine (CuPc) as both the interface modifier and dopant. The resultant planar PSC yields a power conversion efficiency of 14.8%, ∼30% higher than that based on the bare carbon electrode. This is due to higher work function and better hole extraction properties of the CuPc-modified carbon electrodes. The simple modification process of the carbon electrode has potential applications for large-scale fabrication. We further applied such electrodes in large-area solar modules and flexible solar cells, demonstrating their capability of upscaling and flexibility.