Fabrication of the (Y2O3:Yb–Er)/Bi2S3 composite film for near-infrared photoresponse

Abstract

Harvest of near infrared (NIR) radiation in photovoltaic devices is highly desirable as it is recognized as a potential pathway to break the Shockley–Queisser limit of solar conversion efficiency. Here, (Y₂O₃:Yb–Er)/Bi₂S₃ composite films with photoactive current generation under NIR light excitation were fabricated by electro-deposition and a simple successive ionic layer adsorption and reaction (SILAR) method. The composite films consist of homogeneous crystalline particles of Y₂O₃ with a lamellar morphology covered by Bi₂S₃ nanoparticles. Upon excitation by a 980 nm laser, the Y₂O₃:Yb–Er layer in the composite film converts NIR photons into visible emissions through upconversion, which is absorbed by the covered Bi₂S₃ nanoparticles and leads to the generation of photoelectrons. With the use of a standard electrochemical cell where the composite film serves as the photoanode, we demonstrate robust photocurrent generation in aqueous solution. This study suggests a promising strategy for the harvesting of NIR radiation in solar cells, photocatalysts, and infrared photo-detectors.