Chemical Vapor Deposition of Transparent, p-Type Cuprous Bromide Thin Films

The semiconductors CuX (X = Cl, Br, or I) are high-mobility p-type transparent conductors, promising for use in thin film optoelectronic devices such as perovskite photovoltaics. These devices require smooth, pinhole free films that are tens of nanometers thick but uniform across tens of centimeters. Chemical vapor deposition (CVD), an established and scalable process, can provide excellent throughput, conformality, and uniformity on such large areas. However, no prior CVD method could produce continuous thin films of any cuprous halide. We have established such a method, preparing CuBr thin films by reaction between HBr gas and vinyltrimethylsilane(hexafluoroacetylacetonato)copper(I). Our method not only provides the desired device-quality films but also opens up the possibility of a general route to CVD of other metal halides.