Han Dengbao, Imran Muhammad, Zhang Mengjiao, Chang Shuai, Wu Xian-Gang, Zhang Xin, Tang Jialun, Wang Mingshan, Ali Shmshad, Li Xinguo, Yu Gang, Han Junbo, Wang Lingxue, Zou Bingsuo, Zhong Haizheng
NUST Institute of Civil Engineering (NICE) , National University of Sciences and Technology (NUST) , NUST Campus, H-12 , Islamabad 44000 , Pakistan.
Wuhan National High Magnetic Field Center and School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China.
ACS Nano. 2018 Aug 28;12(8):8808-8816. doi: 10.1021/acsnano.8b05172. Epub 2018 Aug 17.
In this paper, we reported the in situ fabrication of highly luminescent formamidinium lead bromide (FAPbBr) nanocrystal thin films by dropping toluene as an anti-solvent during the spin-coating with a perovskite precursor solution using 3,3-diphenylpropylamine bromide (DPPA-Br) as a ligand. The resulting films are uniform and composed of 5-20 nm FAPbBr perovskite nanocrystals. By monitoring the solvent mixing of anti-solvent and precursor solution on the substrates, we illustrated the difference between the ligand-assisted reprecipitation (LARP) process and the nanocrystal-pinning (NCP) process. This understanding provides a guideline for film optimization, and the optimized films obtained through the in situ LARP process exhibit strong photoluminescence emission at 528 nm, with quantum yields up to 78% and an average photoluminescence lifetime of 12.7 ns. In addition, an exciton binding energy of 57.5 meV was derived from the temperature-dependent photoluminescence measurement. More importantly, we achieved highly efficient pure green perovskite based light-emitting diode (PeLEDs) devices with an average external quantum efficiency (EQE) of 7.3% (maximum EQE is 16.3%) and an average current efficiency (CE) of 29.5 cd A (maximum CE is 66.3 cd A) by adapting a conventional device structure of ITO/PEDOT:PSS/TFB/perovskite film/TPBi/LiF/Al. It is expected that the in situ LARP process provides an effective methodology for the improvement of the performance of PeLEDs.
在本文中，我们报道了通过在旋涂钙钛矿前驱体溶液过程中滴加甲苯作为反溶剂，原位制备高发光性的甲脒铅溴（FAPbBr）纳米晶体薄膜，其中使用3,3-二苯基丙胺溴化物（DPPA-Br）作为配体。所得薄膜均匀，由5-20 nm的FAPbBr钙钛矿纳米晶体组成。通过监测反溶剂与前驱体溶液在基板上的溶剂混合情况，我们阐明了配体辅助再沉淀（LARP）过程与纳米晶体钉扎（NCP）过程之间的差异。这种认识为薄膜优化提供了指导，通过原位LARP过程获得的优化薄膜在528 nm处表现出强烈的光致发光发射，量子产率高达78%，平均光致发光寿命为12.7 ns。此外，通过温度相关的光致发光测量得出激子结合能为57.5 meV。更重要的是，我们通过采用ITO/PEDOT:PSS/TFB/钙钛矿薄膜/TPBi/LiF/Al的传统器件结构，实现了高效的纯绿色钙钛矿基发光二极管（PeLEDs）器件，平均外量子效率（EQE）为7.3%（最大EQE为16.3%），平均电流效率（CE）为29.5 cd/A（最大CE为66.3 cd/A）。预计原位LARP过程为提高PeLEDs的性能提供了一种有效的方法。
