Synthesis and Characterization of V-Doped β-In2S3 Thin Films on FTO Substrates

Intermediate band semiconductors have raised interest as materials to both enhance photovoltaics' efficiency and promote photocatalytic activity driven by visible light. The present work shows the synthesis of In2S3 doped with four different ratios of V using the ILGAR technique. This nebulize-spray based technique allows the deposition of In2(V)S3 thin layers controlling the layer thickness and providing high reliability on sample preparation. The samples have been characterized by X-ray diffraction, electron microscopy, profilometry, UV–vis spectroscopy, inductively coupled plasma mass spectrometry, X-ray photoemission spectroscopy, surface photovoltage spectroscopy, time-resolved microwave conductivity, photoelectrochemical, photoluminescence measurements, and electrochemical impedance spectroscopy. An optimum of 1.4% V content yielded the highest enhancement of photocurrent density compared to undoped In2S3. The results suggest that the inclusion of V in the In2S3 at 1.4% yields a high amount of in-gap levels within the crystalline structure that causes a Fermi energy level shift, which also induces the shift of the level of both valence and conduction bands.