Solution-Processed Ag-TiO₂ Nanostructure-Based Schottky Junction Thin Films for Narrowband Hot-Electron Photodetectors

It is not very easy to capture hot plasmonic electrons for photodetection in a photodetector. In this work, an in situ grown Ag-TiO 2 nano-Schottky junction thin film that contains a highly dense silver (Ag) nanoparticle (NP) surrounded by TiO 2 is deposited by a solution-processed technique. This Ag-TiO 2 nano-Schottky junction has a low barrier height and a high interface area with the least interface state, which enables efficient hot-electron transfer to the conduction band of TiO 2, which is realized in the external quantum efficiency (EQE) data. This EQE data show intense photocurrent formation in the region of plasmonic absorption of Ag NP, indicating the primary contribution of hot electrons on photocurrent production. As a consequence, a narrowband photodetector with full width at half-maximum (FWHM) of ∼55 nm is fabricated by utilizing this Ag-TiO 2 nano-Schottky junction thin film. Moreover, due to the high density of the Ag NP, the photodetector shows good detectivity in combination with fast response time. This photodetector is fabricated on a glass substrate in a photoconductor geometry that shows a peak detectivity of 3.19 × 10 11 Jones at 420 nm with a response time of ∼2 s.