Near-Infrared-II Photodetectors Based on Silver Selenide Quantum Dots on Mesoporous TiO 2 Scaffolds

作者：Neil Graddage, Jianying Ouyang, Jianping Lu, Ta‐Ya Chu, Yanguang Zhang, Zhao Li, Xiaohua Wu, Patrick R. L. Malenfant, Ye Tao · 发表于：ACS Applied Nano Materials · 年份：2020 · DOI：10.1021/acsanm.0c02686 · 被引用次数：31 · 研究领域：Quantum Dots Synthesis And Properties、Chalcogenide Semiconductor Thin Films、Perovskite Materials and Applications

Biosensing applications are driving an increase in demand for low-cost photodetectors with sensitivity between 1000 and 1400 nm. Recently, the sensitivity of Ag 2 Se colloidal quantum dot based devices in this wavelength range has been observed. In this work we make the first demonstration of an Ag 2 Se photodiode device with sensitivity in this entire range. By employing secondary phosphine to elevate the precursor reactivity, we achieved accurate size control of the Ag 2 Se nanocrystals with a distinct excitonic absorption peak. These nanocrystals were deposited from solution into a mesoporous TiO 2 scaffold, similar to that used in dye-sensitized solar cells, to increase the light absorption and charge separation and reduce the exciton diffusion length. By incorporation of a suitable hole-transporting layer between the active layer and Ag anode, the resulting devices showed a responsivity of 4.17 mA/W at a wavelength of 1200 nm. These results demonstrate that Ag 2 Se colloidal quantum dots offer a low-toxicity route for low-cost fabrication of near-infrared photodetectors.