Sargent Joint Research Center, Wuhan National Laboratory for Optoelectronics (WNLO), School of Optical and Electronic Information, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, China.
Optics Valley Laboratory, 1037 Luoyu Road, Wuhan, Hubei 430074, China.
ACS Appl Mater Interfaces. 2023 Mar 8;15(9):12061-12069. doi: 10.1021/acsami.2c22774. Epub 2023 Feb 27.
PbS colloidal quantum dot (CQD) infrared photodiodes have attracted wide attention due to the prospect of developing cost-effective infrared imaging technology. Presently, ZnO films are widely used as the electron transport layer (ETL) of PbS CQDs infrared photodiodes. However, ZnO-based devices still suffer from the problems of large dark current and low repeatability, which are caused by the low crystallinity and sensitive surface of ZnO films. Here, we effectively optimized the device performance of PbS CQDs infrared photodiode via diminishing the influence of adsorbed HO at the ZnO/PbS CQDs interface. The polar (002) ZnO crystal plane showed much higher adsorption energy of HO molecules compared with other nonpolar planes, which could reduce the interface defects induced by detrimentally adsorbed HO. Based on the sputtering method, we obtained the [002]-oriented and high-crystallinity ZnO ETL and effectively suppressed the adsorption of detrimental HO molecules. The prepared PbS CQDs infrared photodiode with the sputtered ZnO ETL demonstrated lower dark current density, higher external quantum efficiency, and faster photoresponse compared with the sol-gel ZnO device. Simulation results further unveiled the relationship between interface defects and device dark current. Finally, a high-performance sputtered ZnO/PbS CQDs device was obtained with a specific detectivity of 2.15 × 10 Jones at -3 dB bandwidth (94.6 kHz).
PbS 胶体量子点 (CQD) 红外光电二极管由于开发具有成本效益的红外成像技术的前景而受到广泛关注。目前，氧化锌 (ZnO) 薄膜被广泛用作 PbS CQD 红外光电二极管的电子传输层 (ETL)。然而，基于 ZnO 的器件仍然存在暗电流大、重复性差等问题，这是由于 ZnO 薄膜的结晶度低和表面敏感。在这里，我们通过减少 ZnO/PbS CQD 界面上吸附的 HO 的影响，有效地优化了 PbS CQD 红外光电二极管的器件性能。极性 (002) ZnO 晶面与其他非极性晶面相比，对 HO 分子具有更高的吸附能，从而减少了由有害吸附的 HO 引起的界面缺陷。基于溅射法，我们获得了[002]取向和高结晶度的 ZnO ETL，并有效地抑制了有害 HO 分子的吸附。与溶胶-凝胶 ZnO 器件相比，制备的溅射 ZnO ETL 的 PbS CQD 红外光电二极管具有更低的暗电流密度、更高的外量子效率和更快的光响应。模拟结果进一步揭示了界面缺陷与器件暗电流之间的关系。最后，获得了一种高性能的溅射 ZnO/PbS CQD 器件，在 -3 dB 带宽 (94.6 kHz) 下的特定探测率为 2.15×10 琼斯。
