Li Yuyang, Liu Hui, Ding Li, Li Liqi, Wang Lixiang, Yang Deren, Fang Yanjun
State Key Laboratory of Silicon and Advanced Semiconductor Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China.
Shangyu Institute of Semiconductor Materials, Shaoxing 312300, P. R. China.
ACS Appl Mater Interfaces. 2024 May 15;16(19):25033-25041. doi: 10.1021/acsami.4c01567. Epub 2024 May 3.
Perovskite nanocrystals (PNCs) offer unique advantages in large-area and thick-film deposition for X-ray detection applications due to the decoupling of the crystallization of perovskite from film formation, as well as their low-temperature and scalable deposition methods. However, the partial detachment of long-chain ligands in PNCs during the purification process would lead to the exposure of surface defects, making it challenging to ensure efficient charge carrier extraction and stable X-ray detection. In this study, we propose a beneficial strategy that involves the in situ reparation of these exposed defects with sodium bromide (NaBr) during the purification process to construct CsPbBr PNC-organic bulk heterostructure X-ray detectors. The NaBr-passivated PNCs exhibit stronger photoluminescence intensity and lower trap density in films compared to those of the control samples, confirming the effective passivation of halide vacancy defects. Furthermore, the NiO hole transport layer with remarkable electron blocking capability is introduced to further suppress the dark current of the devices. Consequently, the optimal devices exhibit a large sensitivity of 4237 μC Gy cm and a low dark current density of 10 nA cm, as well as improved operational stability, which allows for high-contrast and low-dose X-ray imaging applications.
由于钙钛矿的结晶与成膜过程解耦，以及其低温且可扩展的沉积方法，钙钛矿纳米晶体（PNCs）在用于X射线检测应用的大面积和厚膜沉积方面具有独特优势。然而，在纯化过程中PNCs中长链配体的部分脱离会导致表面缺陷暴露，这使得确保有效的电荷载流子提取和稳定的X射线检测具有挑战性。在本研究中，我们提出了一种有益的策略，即在纯化过程中用溴化钠（NaBr）原位修复这些暴露的缺陷，以构建CsPbBr PNC-有机本体异质结X射线探测器。与对照样品相比，NaBr钝化的PNCs在薄膜中表现出更强的光致发光强度和更低的陷阱密度，证实了卤化物空位缺陷的有效钝化。此外，引入具有显著电子阻挡能力的NiO空穴传输层以进一步抑制器件的暗电流。因此，最佳器件表现出4237 μC Gy cm的高灵敏度和10 nA cm的低暗电流密度，以及改善的操作稳定性，这使其适用于高对比度和低剂量X射线成像应用。
