High-efficiency (>20%) planar carbon-based perovskite solar cells through device configuration engineering.

Carbon-based perovskite solar cells (C-PSCs) have attracted widespread research interest because of their excellent stability. However, the power conversion efficiency (PCE) of C-PSCs, especially planar C-PSCs, lags far behind the certified efficiency (25.5%) of metal-based PSCs. The simple architecture of planar C-PSCs imparts stringent requirements for device configuration. In this study, we fabricated high-performance planar C-PSCs through device configuration engineering in terms of the perovskite active layer and carbon electrode. Through the combination of component and additive engineering, the crystallization and absorption profiles of perovskite active layer have been improved, which afforded sufficient photogenerated carriers and decreased nonradiative recombination. Furthermore, the mechanical and physical properties of carbon electrode were evaluated comprehensively to regulate the back-interface contact. Based on the compromise of the flexibility and conductivity of carbon film, an excellent back-interface contact has been formed, which promoted fast interface charge transfer, thereby decreasing interface recombination and improving carrier collection efficiency. Finally, the as-prepared devices achieved a remarkable PCE of up to 20.04%, which is a record-high value for planar C-PSCs. Furthermore, the as-prepared devices exhibited excellent long-term stability. After storage for 1000 h at room temperature and 25% relative humidity without encapsulation, the as-prepared device retained 94% of its initial performance.