Reduced trap density and mitigating the interfacial losses by placement of 2D dichalcogenide material at perovskite/HTM interface in a dopant free perovskite solar cells

Solution-processed photovoltaics employing perovskite as light harvester are the next generation future energy source owing to its low manufacturing cost and potential to achieve high power conversion efficiency. Significant emphasis has been laid on the performance-related investigations, however the long-term instability under operational conditions and device reproducibility obstruct its potential commercial endeavour. Herein, by tweaking the energy level alignment between the hole-transport layer and perovskite, by the placement of a thin 2D-MoS₂ interlayer, we demonstrate suppressed interfacial charge accumulation, fast charge extraction, and subsequently improved photovoltaic performances. Notably, with the usage of a dopant free hole transport materials, a power conversion efficiency of 18.54% with significantly upgraded open circuit voltage (V_oc) and FF was recorded. The stability measurement shows that the resulting 2D-MoS₂ supported dopant-free hole selective layers exhibit notable moisture stability under ambient conditions. Our study put forward the profound experimental understanding of 2D-transition metal dichalcogenides as an agent to engineering the interface, enlightening the power conversion efficiency and lifetime of the perovskite solar cells.