Fabrication of nanocrystal ink based superstrate-type CuInS2 thin film solar cells

A CuInS2 (CIS) nanocrystal ink was applied to thin film solar cell devices with superstrate-type configuration. Monodispersed CIS nanocrystals were synthesized by a colloidal synthetic route and re-dispersed in toluene to form an ink. A spray method was used to coat CIS films onto conducting glass substrates. Prior to CIS film deposition, TiO2 and CdS thin films were also prepared as a blocking layer and a buffer layer, respectively. We found that both a TiO2 blocking layer and a CdS buffer layer are necessary to generate photoresponses in superstrate-type devices. The best power conversion efficiency (similar to 1.45%) was achieved by the CIS superstrate-type thin film solar cell device with 200 and 100 nm thick TiO2 and CdS films, respectively.