Intermediate-Controlled Interfacial Engineering for Stable and Highly Efficient Carbon-Based PSCs

A major bottleneck hindering the performance and commercial application of cost-effective carbon-based perovskite solar cells (C-PSCs) is the contact issue at the interface of the perovskite layer and the carbon counter electrode. Herein, a new approach of intermediate-controlled interfacial engineering (IIE) utilizing an ultra-low-cost acetylene black material is developed for the first time that can improve the interfacial contact of C-PSCs. We achieved both high efficiency (16.41%) without hole-transport materials and good stability as a result of the optimal heterogeneous interfacial contact. Devices without any encapsulation consistently exhibit excellent environmental stability, retaining 93% of their original efficiency by storing in an ambient atmosphere (30 °C, 30% RH) for 2000 h and achieving 81% of their original efficiency by storing in a terrible air environment (85 °C, 65% RH) for 312 h. In addition, to acquire a deep understanding of carrier transport, a comparison of heterogeneous interfaces fabricated using different methods has been undertaken. In C-PSCs fabricated by the IIE method, the lower radioactive recombination and faster carrier transfer result in a shorter carrier lifetime. We present a promising future for the industrialization of C-PSCs by reducing the costs and improving the performance.