Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 12, Issue 34, Pages 38341-38349Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.0c09180
Keywords
antimony selenide; photodetector; thin film; semiconductor sensitizer; p-Sb2Se3/n-TiO2 heterojunction; surface oxidation; oxygen interstitial
Funding
- NSFC [21571086, 11604125, 51572111]
- Natural Science Foundation of Jiangsu Province [BK20141297, BK20160522]
- Cultivating Project of Young Academic Leader
- Research Foundation of Jiangsu University [11JDG071]
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Semiconductor-sensitized TiO2 thin films with long-term air stability are attractive for optoelectronic devices and applications. Herein, we demonstrate the potential of the TiO2 thin film (similar to 800 nm in thickness) sensitized with a Sb2Se3 layer (similar to 350 nm) grown from solution spin coating and processed by annealing recrystallization at 300 degrees C for high-performance optical detection. The type-H band alignment, p-Sb2Se3/n-TiO2 heterojunction, and narrow band gap of Sb2Se3 (similar to 1.2S eV) endow the film photodetector with a large photo-current, high switching stability and on/off ratio (>10(3)), and fast response speeds (<20 ms) under the broadband visible-near-infrared irradiation in a zero-bias self-powered photovoltaic mode. In particular, the photodetector shows notable resistance to oxidation and moisture for long-term operation, which is linked to the modest surface oxidation (Sb-O) of Sb2Se3, as verified by X-ray photoelectron spectroscopy. The first-principles calculations show that a low and medium concentration of oxygen substitution for Se (O-Se) and oxygen interstitial (O-i) with negative formation energies can lead to such a moderate surface oxidation but do not generate impurity states or just introduce a shallow-level acceptor state in the electronic structures of Sb2Se3 without degrading its optoelectronic performance. Our theoretical results offer a rational explanation for the air-stable and oxidation/moisture-resistant characteristics in moderately oxidized Sb2Se3 and may shed light on the surface oxidation-property relationship studies of other nonoxide semiconductor-sensitized devices.
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