Gong Wei, Wang Peng, Li Jingjie, Li Jingzhen, Zhang Yongzhe
Faculty of Materials and Manufacturing, Key Laboratory of Advanced Functional Materials, Ministry of Education, Beijing University of Technology, Beijing 100124, China.
Faculty of Information Technology, Key Laboratory of Optoelectronics Technology, Ministry of Education, Beijing University of Technology, Beijing 100124, China.
J Phys Chem Lett. 2022 Sep 8;13(35):8327-8335. doi: 10.1021/acs.jpclett.2c02034. Epub 2022 Aug 30.
The responsivities of colloidal quantum dot (CQD) photodiodes are not satisfactory (∼0.3 A W) due to the lack of gain. Here, visible-near-infrared PbS CQD photodiodes with a peak responsivity of ∼1 A W and external quantum efficiencies larger than 100% are demonstrated. The gain is realized by electron tunneling injection through the Schottky junction (PbS-EDT/Au) with barrier height reduced to 0.27 eV, originating from the capture of photogenerated holes at the negatively charged acceptor traps generated in the oxidized hole-transport layer PbS-EDT. The resulting device exhibits a peak detectivity of ∼8 × 10 jones at -1 V. Additionally, the response speed (400 μs) is not sacrificed by the trap states because of the dominated faster electron drift motion in the fully depleted device. Our results provide an accurate elucidation of the gain mechanism in CQD photodiodes and promise them great potential in weak light detection.
由于缺乏增益，胶体量子点（CQD）光电二极管的响应度并不理想（约0.3 A/W）。在此，展示了具有约1 A/W的峰值响应度和大于100%的外量子效率的可见-近红外PbS CQD光电二极管。增益是通过电子隧穿注入肖特基结（PbS-EDT/Au）实现的，其势垒高度降低到0.27 eV，这源于在氧化空穴传输层PbS-EDT中产生的带负电的受体陷阱对光生空穴的捕获。所得到的器件在-1 V时表现出约8×10琼斯的峰值探测率。此外，由于在完全耗尽的器件中电子漂移运动占主导且速度更快，陷阱态并未牺牲响应速度（400 μs）。我们的结果准确阐明了CQD光电二极管中的增益机制，并预示着它们在弱光检测方面具有巨大潜力。
