异质形核构筑的高效钙钛矿发光二极管

Efficient perovskite light-emitting diodes based on heterogeneous nucleation

钙钛矿薄膜的制备方法对发光层的性质及发光二极管(LED)的性能有较大影响。将无机钙钛矿CsPbBr3量子点引入到反溶剂中作为形核位点诱导CH3NH3PbI3薄膜异质形核,然后将该薄膜应用于制备发光二极管。结果表明:应用这种异质形核方法不仅能有效降低CH3NH3PbI3薄膜中晶粒尺寸,提高薄膜质量,限制载流子扩散,且量子点表面多余的配体基团可以对CH3NH3PbI3薄膜中表面及晶界的缺陷产生钝化作用,减小非辐射复合,从而增强载流子寿命和提高辐射复合效率;应用该CH3NH3PbI3薄膜作为发光层制备的LED器件,在低电压下具有较低漏电流,最大外量子效率达到0.17%,相比于基础器件提高了3倍。研究结果将为高质量钙钛矿薄膜及发光器件的制备提供有效途径。

The preparation methods of perovskite films have a great influence on properties of emissive layers and the performance of light-emitting diodes.Inorganic perovskite CsPbBr3 quantum dots were introduced into the antisolvent as nucleation sites to induce heterogeneous nucleation of CH3NH3PbI3film.Then,the CH3NH3PbI3films were used to prepare light-emitting diodes.The result indicates that such heterogeneous nucleation method can effectively lower grain size in CH3NH3PbI3films,improve film quality and restrict carrier diffusion.In addition to these,the excess ligand groups on the surface of quantum dots can passivate defects located on surfaces and grain boundaries in CH3NH3PbI3films and decrease non-radiation recombination,thus enhancing carrier lifetime and radiative recombination efficiency.The light-emitting diodes fabricated by using the above-mentioned CH3NH3PbI3films as the luminescent layer showed low leakage current at a low voltage,and the maximum external quantum efficiency reached 0.17%,3times higher than that of basic components.The result provides an effective strategy to fabricate high-quality perovskite films and high-performance light-emitting devices.