Efficient and stable low-cost perovskite solar cells enabled by using surface passivated carbon as the counter electrode

Abstract

Carbon-based hole-transport-layer free perovskite solar cells (C-PSCs) have attracted much attention due to their low cost, simple preparation process and high stability. However, the efficiency of the C-PSCs is far behind the most advanced metal-based devices, which is mainly due to the carrier recombination at the interface of the carbon electrode and the perovskite layer. Herein, a poly(ethylene glycol) (PEG) passivated carbon electrode was hot-pressed onto the perovskite to enhance the combination of the carbon electrode and the perovskite and improve the interface carrier transport. Through PEG passivation, the bending strength of the carbon electrode was improved obviously. Meanwhile, the EIS and TPV/TPC results show that the carrier recombination at the perovskite/carbon interface is inhibited. After passivation, the power conversion efficiency of the C-PSCs reached 11.52%, which was 25.6% higher than that of the non-passivated devices. The device can maintain 87% of its initial efficiency after being stored in a humid environment (RH ≈ 50–60%) for more than 50 days without packaging. This simple manufacturing process of PSCs paves the way for the commercialization of new photovoltaic technology.