Enhanced optoelectronic properties of solution-processed metal-chalcogenide devices via hydrogen-driven post-annealing

Here, we report a general strategy to obtain low-temperature processed high-quality and large-area metal chalcogenide (CdSe) semiconductors from precursor based benign solution process. Using hydrogen-driven post thermal annealing, the deposited thin films enable expeditious formation at relatively low process temperature (<350°C), which are easily transformed into the corresponding high-quality and large-area films with less defect states and more crystalline structures, indicating enhanced electro-optical properties. The improved metal chalcogenide alloy thin-films are successfully synthesized and the versatility of this facile route is demonstrated by fabricating large-area thin-film-transistors and optoelectronic devices on 4-inch silicon and 2.5-inch borosilicate glass substrates in air ambient. The polycrystalline hydrogenated CdSe-based thin-film-transistor (TFT) exhibited relatively good electro-optical properties such as a maximum field-effect mobility larger than 150 cm² V⁻¹s⁻¹ with on/off current ratio of> 10⁷ and subthreshold slope of< 1 V decade⁻¹ as well as improved responsivity (9.64 ×10⁻³ AW⁻¹) and switching speed. To validate our findings, we discussed the detailed mechanism of the reduction of defect states and precisely designed thin film synthesis with process temperature, time, the correlation with molecular composition, physical structure of the films, and the optoelectronic performance of CdSe TFTs.