氯化甲胺对甲胺铅溴钙钛矿单晶的钝化

Passivation of methylamine lead bromide perovskite single crystal by methylamine chloride

为了减少甲胺铅溴(MAPbBr3)钙钛矿单晶的表面缺陷以提高其光电性能,采用氯化甲胺(MACl)的异丙醇溶液对机械打磨后的MAPbBr_(3)单晶进行钝化。通过扫描电子显微镜(SEM)、光致发光谱(PL)、时间分辨光致发光衰减谱(TRPL)、X射线衍射图谱(XRD)、X射线光电子能谱(XPS)和紫外光电子能谱(UPS)对MACl钝化后的MAPbBr_(3)单晶的结构与形貌进行表征和分析;采用钝化后的单晶制备光电探测器,考察MACl钝化对MAPbBr_(3)单晶的光电性能的影响。结果表明:经MACl钝化,机械打磨后的MAPbBr_(3)单晶表面重新结晶,载流子寿命增大约4.5倍,在形貌优化的同时有效减少了单晶的表面缺陷。氯离子的引入改变了单晶表面的晶格间距与能带结构,增大了单晶与电极之间的势垒,可使暗电流减少2个数量级,光暗电流比提高1个数量级,探测率提高近5倍。MACl钝化法简易高效,成本低廉,为MAPbBr_(3)钙钛矿单晶高性能光电探测器的开发应用提供了可行性方案。

To reduce the surface defects of methylamine lead bromide(MAPbBr_(3)) perovskite single crystal and improve its photoelectric properties, methylamine chloride(MACl) isopropanol solution was used to passivate the mechanically polished MAPbBr_(3)single crystal. The structure and morphology of MACl-passivated MAPbBr_(3)single crystal were characterized by SEM, PL, TRPL, XRD, XPS, and UPS, and the photodetector based on the passivated single crystal was fabricated to analyze the effect of MACl passivation on photoelectric properties of MAPbBr_(3)single crystal. The results have shown that MACl passivation can recrystallize the polished surface of MAPbBr_(3)single crystal, optimize its morphology, reduce its surface defects, and increase the carrier lifetime by 4.5 times. Furthermore, the introduction of Cl-changes the lattice spacing and bandgap on the surface of the single crystal, increases the potential barrier between the single crystal and the electrode, reduces the dark current by two orders of magnitude, improves the light-dark current ratio by one order of magnitude, and enhances the detectivity by nearly 5 times. This feasible, efficient, and low-cost MACl passivation strategy has proved great practical potential in the development and application of MAPbBr_(3)perovskite single crystal based high-performance photodetector.