Sn-Pb binary and mixed-halide perovskite thin films by low-pressure chemical vapor deposition

Prof. Christopher Arendse
Physics 120
Prof. Suchi Guha

Since its first application as light absorbing materials in photovoltaic technology, perovskite solar cells (PSCs) have achieved a remarkable certified record power conversion efficiency (PCE) of over 25% in just over a decade. However, hybrid perovskite absorbers still face the issue of chemical instability as they degrade under continued exposure to moisture, light illumination, and UV light and are unstable at high temperatures. These instabilities are related to the deposition method used and the intrinsic properties of the material. We have demonstrated the deposition of pure, polycrystalline, smooth, and compact MAPbI3 perovskite films, using a sequential low-pressure chemical vapor deposition (LPCVD) method in a single reactor. This material was incorporated into a planar single-junction PSC (with no additives or additional interfacial engineering) that was fabricated, stored and tested under open-air conditions, yielding a best PCE of 11.7%. The solar cell maintains 85% of its performance up to 13 days in the open air with a relative humidity up to 80%.

This LPCVD method was further developed to produce mixed-halide and Sn-Pb perovskite thin films. We will report on the deposition procedure of these thin films and its resultant structural, compositional and optical properties. Furthermore, the impact of Cl-doping on the PSC performance will be discussed.