Broadband NIR photoelectronic performance for sunlight‐induced photocurrent from (NaYF4:Yb‐Er)/BiOI hybrid films

Abstract The fabrication and near‐infrared optoelectronic performance of the (Na YF 4 :Yb‐Er)/Bi OI upconversion phosphor/semiconductor hybrid films are reported. The composite films were fabricated by a simple electro‐deposition and successive ionic layer adsorption and reaction ( SILAR ) method. We observed efficient upconversion emissions in the film of Na YF 4 :Yb‐Er upon irradiation by near‐infrared part of simulated sunlight, and the UC emission is drastically quenched in the composite film (Na YF 4 :Yb‐Er)/Bi OI . More importantly, this composite film displays unusual negative photoresponse to near‐infrared part of simulated sunlight when used in a standard electrochemical cell where the composite film serves as the photoanode. This result may pave the way for potential application of this hybrid films for the development of novel photovoltaic and infrared optoelectronic devices.