Stabilizing high-humidity perovskite solar cells with MoS2 hybrid HTL

Abstract

The obstacle to the industrialization of perovskite solar cells (PSC) technology lies in their stability. This work rationalizes the PSC design with the employment of 2D-MoS2 as the hybrid hole transport layer (HTL). MoS2 was selected due to its unique optoelectronic and mechanical properties that could enhance hole extraction and thus boost the performance and stability of PSC devices. Five concentrations indicated MoS2 nanosheets were directly deposited onto the perovskite layer via the facile spin coating method. The electrochemical exfoliation and liquid exchange methods were demonstrated to obtain the lateral size of MoS2 nanosheets and further discussed their microscopic and spectroscopic characterizations. Remarkably, the optimum thickness and the excellent device increased the stability of the PSC, allowing it to maintain 45% of its degradation percentage (ΔPCEPCE) for 120 h with high relative humidity (RH = 40–50%) in its vicinity. We observed that lithium-ion can intercalate into the layered MoS2 structure and reduce the interfacial resistance of perovskite and the HTL. Most importantly, the 2D-MoS2 mechanism’s effect on enabling stable and efficient devices by reducing lithium-ion migration in the HTL is demonstrated in this work to validate the great potential of this hybrid structure in PSC applications.