Suchergebnisse

Ministry of Science and Technology, Taiwan (104-2221-E-110-012-MY3, 107-2221-E-110-004-MY3); National Natural Science Foundation of China (51602309, U1605245). ; The temperature-dependent polarized photoluminescence spectra of nonpolar ZnO samples were investigated by 263 nm laser. The degree of polarization (DOP) of m-plane quantum wells changes from 76% at 10 K to 40% at 300 K, which is much higher than that of epilayer. The strong anisotropy was presumably attributed to the enhanced confinement effect of a one-dimension confinement structure formed by the intersection of quantum well and basal stacking fault. The polarization of laser beam also has an influence on the DOP. It is assumed that the luminescence polarization should be affected not only by the in-plane strains but also the microstructural defects, which do modify the electronic band structure. ; Ministry of Science and Technology, Taiwan 104-2221-E-110-012-MY3,107-2221-E-110-004-MY3; National Natural Science Foundation of China U1605245,51602309; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

Organometal halide perovskites can be processed from solutions at low temperatures to form crystalline direct-bandgap semiconductors with promising optoelectronic properties(1-5). However, the efficiency of their electroluminescence is limited by non-radiative recombination, which is associated with defects and leakage current due to incomplete surface coverage(6-9). Here we demonstrate a solution-processed perovskite light-emitting diode (LED) based on self-organized multiple quantum wells (MQWs) with excellent film morphologies. The MQW-based LED exhibits a very high external quantum efficiency of up to 11.7%, good stability and exceptional highpower performance with an energy conversion efficiency of 5.5% at a current density of 100 mA cm(-2). This outstanding performance arises because the lower bandgap regions that generate electroluminescence are effectively confined by perovskite MQWs with higher energy gaps, resulting in very efficient radiative decay. Surprisingly, there is no evidence that the large interfacial areas between different bandgap regions cause luminescence quenching. ; Funding Agencies|National Basic Research Program of China-Fundamental Studies of Perovskite Solar Cells [2015CB932200]; Natural Science Foundation of Jiangsu Province, China [BK20131413, BK20140952, BM2012010]; National Natural Science Foundation of China [11474164, 51522209, 91433204, 61405091, 11474249]; National 973 Program of China [2015CB654901]; Jiangsu Specially-Appointed Professor programme; Synergetic Innovation Center for Organic Electronics and Information Displays; Fundamental Research Funds for the Central Universities [2015FZA3005]; China Postdoctoral Science Foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Swedish Research Council (VR) [330-2014-6433]; European Commission Marie Sklodowska-Curie actions [691210, INCA 600398]