A novel functionalized ferrocene derivative as a hole transport material for efficient perovskite solar cells: insight into the ultrafast interfacial carrier dynamics and charge transport

Abstract

Recently, lead halide perovskites have been developing rapidly in the field of photo-electric functional devices. The key to further enhancing its potential in thin-film photo-electronic devices lies in understanding the charge (electron/hole) separation process and its transfer across the interface. In addition to optimizing the preparation conditions, finding excellent electron/hole transport materials is a matter of priority for improving the efficiency of charge separation between different functional layers in optoelectronic devices. In this work, a novel organic metallic functionalized ferrocenyl acetylacetone (FAAT) derivative was developed as a hole transport material (HTM). The very stable lead halide perovskite material and CsPbBr₃ quantum dots are used as carrier donors, and data from TRPL show that the addition of FAAT can improve the carrier separation efficiency at the quantum dot interface by at least 64.6%. Moreover, the excited state dynamics data from transient absorption experiments also show that the excited state dynamics of quantum dots rapidly change from the fluorescence relaxation process (2440 ps) to the hole transfer process (263 ps) after the addition of FAAT. FAAT was used as a dopant-free HTM to improve the photovoltaic performance of the inverted perovskite solar cells (PSCs). As a result, the optimal FAAT-based device efficiency reached 19.05%. All these studies indicate that FAAT is expected to be a cost-effective and chemically stable hole transport material for efficient PSCs.