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 (iV_oc ) of 1.133 V.