摘要
Substitution of lead(Pb)with tin(Sn)is a very important way to reduce the bandgap of metal halide perovskite for applications in solar cells,and near infrared(NIR)light-emitting diodes(LEDs),etc.However,mixed Pb/Sn perovskite becomes very disordered with high trap density when the Sn molar ratio is less than 20%.This limits the applications of mixed Pb/Sn perovskites in optoelectronic devices such as wavelength tunable NIR perovskite LEDs(Pe LEDs).In this work,we demonstrate that alkali cations doping can release the microstrain and passivate the traps in mixed Pb/Sn perovskites with Sn molar ratios of less than 20%,leading to higher carrier lifetime and photoluminescence quantum yield(PLQY).The external quantum efficiency(EQE)of Sn_(0.2)Pb_(0.8)-based NIR Pe LEDs is dramatically enhanced from 0.1%to a record value of 9.6%(emission wavelength:868 nm).This work provides a way of making high quality mixed Pb/Sn optoelectronic devices with small Sn molar ratios.
发射波长在800~1000 nm的近红外光源在生物成像、医疗、虹膜识别、光通信等领域有着广泛的应用.传统的基于Ⅲ-Ⅴ族半导体的NIR-LEDs制备工艺复杂,价格较贵.溶液法制备的基于有机半导体和量子点的NIR-LEDs目前仍存在许多问题,最高外量子效率(EQE)仅约4%~8%.Sn-Pb混合钙钛矿具有成本低廉,及在近红外光波段波长连续可调的优势.然而,Sn^(2+)和Pb^(2+)离子半径的差异会导致薄膜内部产生应力和缺陷,光电特性变差.本文证明了离子半径较小的碱金属阳离子(Cs^(+),Rb^(+),K^(+))的掺杂可以释放Sn-Pb混合钙钛矿薄膜内部应力,并起到钝化缺陷的作用.基于碱金属掺杂的Sn-Pb混合钙钛矿的NIR-LED的最高EQE达到了9.6%,高于同波段的有机半导体和量子点的NIR-LEDs.此外,作者还通过调节Sn的比例,获得了发射波长在868~917 nm区间连续可调的高效率NIR-LEDs.
作者
Huanqin Yu
Wenjing Chen
Zhibin Fang
Liming Ding
Bingqiang Cao
Zhengguo Xiao
于焕芹;陈文静;房志斌;丁黎明;曹丙强;肖正国(Hefei National Laboratory for Physical Science at the Microscale,Department of Physics,Key Laboratory of Strongly-Coupled Quantum Matter Physics(CAS),University of Science and Technology of China,Hefei 230026,China;School of Material Science and Engineering,Materials Research Center for Energy and Photoelectrochemical Conversion,University of Jinan,Jinan 250022,China;Center for Excellence in Nanoscience(CAS),Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS),National Center for Nanoscience and Technology,Beijing 100190,China)
基金
the financial support of the National Natural Science Foundation of China(51872161)
Major Program of Shandong Provincial Natural Science Foundation(ZR2017ZB0316)
the financial support of the National Natural Science Foundation of China(51872274)
the Fundamental Research Funds for the Central Universities(WK2060190100)
the National Key Research and Development Program of China(2017YFA0206600)
the National Natural Science Foundation of China(51773045,21772030,51922032,and 21961160720)for financial support。
