Nanoengineering of the Cu2ZnSnS4–TiO2 interface via atomic layer deposition of Al2O3 for high sensitivity photodetectors and solid state solar cells

Abstract

In this work, it is demonstrated that by applying a nanoscale Al₂O₃ film via atomic layer deposition (ALD) to the Cu₂ZnSnS₄–TiO₂ p/n junction, the adverse Sn doping effect is prevented and band alignment is optimized. EDS f-ratio mapping and XANES are used to confirm the purity and nanoscale homogeneity of CZTS. Thanks to the engineered interface by ALD Al₂O₃, high sensitivity photodetectors are designed exhibiting a novel voltage alterable spectral photoresponse. By further integrating a CdS interfacial layer, a TiO₂–Al₂O₃–CZTS/Spiro-OMeTAD/Au solid state nanostructured solar cell is eventually fabricated with an enhanced energy conversion efficiency of 4.2%.