Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, 199 Ren'ai Road, Suzhou, 215123, People's Republic of China.
Cavendish Laboratory, Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK.
Nat Commun. 2018 Sep 24;9(1):3892. doi: 10.1038/s41467-018-06425-5.
Organometal halide perovskites (OHP) are promising materials for low-cost, high-efficiency light-emitting diodes. In films with a distribution of two-dimensional OHP nanosheets and small three-dimensional nanocrystals, an energy funnel can be realized that concentrates the excitations in highly efficient radiative recombination centers. However, this energy funnel is likely to contain inefficient pathways as the size distribution of nanocrystals, the phase separation between the OHP and the organic phase. Here, we demonstrate that the OHP crystallite distribution and phase separation can be precisely controlled by adding a molecule that suppresses crystallization of the organic phase. We use these improved material properties to achieve OHP light-emitting diodes with an external quantum efficiency of 15.5%. Our results demonstrate that through the addition of judiciously selected molecular additives, sufficient carrier confinement with first-order recombination characteristics, and efficient suppression of non-radiative recombination can be achieved while retaining efficient charge transport characteristics.
金属有机卤化物钙钛矿（OHP）是一种很有前途的低成本、高效率发光二极管材料。在二维 OHP 纳米片和小尺寸三维纳米晶分布的薄膜中，可以实现能量漏斗，将激发集中在高效辐射复合中心。然而，由于纳米晶的尺寸分布、OHP 与有机相之间的相分离，这个能量漏斗可能包含低效途径。在这里，我们证明通过添加一种抑制有机相结晶的分子，可以精确控制 OHP 纳米晶的分布和相分离。我们利用这些改进的材料性能，实现了外量子效率为 15.5%的 OHP 发光二极管。我们的结果表明，通过添加精心选择的分子添加剂，可以实现具有一级复合特性的充分载流子限制和高效抑制非辐射复合，同时保留高效的电荷输运特性。
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