Lead Iodide by APCVD for Silicon-Perovskite Tandem Solar Cell Production

Abstract

Recent advancements in silicon-perovskite tandem devices have shown potential to surpass the Shockley-Queisser efficiency limit for an ideal single junction solar cell of 33.7%. However, high-throughput deposition of perovskite on large areas remains challenging. A promising method for scalable perovskite thin film formation is the two-step deposition process, in which a PbI2 thin film is deposited and converted by exposition to an organic halide source like formamidinium iodide (FAI). The approach in particular addresses the rate limitation for the organic components. Thus, a high-rate deposition of inorganic components such as PbI₂ re-mains the missing piece. One promising high throughput deposition technique is atmospheric pressure chemical vapor deposition (APCVD), that was already successfully demonstrated for the deposition of n- and p-type amorphous silicon as well as transparent conductive oxides. This work demonstrates for the first time the application of an industrial APCVD tool for pro-ducing PbI2 thin films. Stationary deposition shows a Gaussian injector slit deposition profile, while for in-line deposition a PbI2 thin film of 365 nm thickness with a maximum rate of 81.2 ± 12.5 nm/min is achieved. High crystallinity is confirmed through X-ray diffraction (XRD), and subsequent wet chemical conversion with a FAI solution yields >500 nm thick perovskite thin films with a maximum implied open circuit voltage (iVoc ) of 1.133 V.