Suchergebnisse

Multidentate molecular additives are widely used to passivate perovskite, yet the role of chelate effect is still unclear. Here, the authors investigate a wide range of additives with different coordination number and functional moieties to establish correlation between coordination affinity and perovskite crystallisation dynamics. Molecular additives are widely utilized to minimize non-radiative recombination in metal halide perovskite emitters due to their passivation effects from chemical bonds with ionic defects. However, a general and puzzling observation that can hardly be rationalized by passivation alone is that most of the molecular additives enabling high-efficiency perovskite light-emitting diodes (PeLEDs) are chelating (multidentate) molecules, while their respective monodentate counterparts receive limited attention. Here, we reveal the largely ignored yet critical role of the chelate effect on governing crystallization dynamics of perovskite emitters and mitigating trap-mediated non-radiative losses. Specifically, we discover that the chelate effect enhances lead-additive coordination affinity, enabling the formation of thermodynamically stable intermediate phases and inhibiting halide coordination-driven perovskite nucleation. The retarded perovskite nucleation and crystal growth are key to high crystal quality and thus efficient electroluminescence. Our work elucidates the full effects of molecular additives on PeLEDs by uncovering the chelate effect as an important feature within perovskite crystallization. As such, we open new prospects for the rationalized screening of highly effective molecular additives. ; Funding Agencies|ERC Starting GrantEuropean Research Council (ERC) [717026]; Swedish Energy Agency EnergimyndighetenSwedish Energy Agency [48758-1, 44651-1]; Swedish Research Council VRSwedish Research Council; NanoLund; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [91833303, 61974098, 62005126]; National Key Research and Development Program [2016YFA0201900]; Jiangsu High Educational Natural Science Foundation [18KJA430012]; 111 ProgramMinistry of Education, China - 111 Project; Collaborative Innovation Center of Suzhou Nano Science and Technology; Collaborative Innovation Center of Suzhou Nano Science Technology; Research Foundation - Flanders (FWO)FWO [12Y7218N, 12Y7221N, G098319N]; KU Leuven Research FundKU Leuven [C14/19/079, 201806920071, 201906830040, 201608530162, 201806460021]; China Scholarship CouncilChina Scholarship Council