General Mild Reaction Creates Highly Luminescent Organic-LigandLacking Halide Perovskite Nanocrystals for Efficient Light-Emitting Diodes
Bin-Bin Zhang†,∇, Shuai Yuan‡,∇, Ju-Ping Ma†,∇, Yang Zhou†,∇, Jingshan Hou§, Xueyuan Chen∥, Wei Zheng∥, Huaibin Shen⊥, Xue-Chun Wang‡, Baoquan Sun‡, Osman M. Bakr#, Liang-Sheng Liao*,‡（廖良生）, and Hong-Tao Sun*,†,∥（孙洪涛）
† College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
‡ Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, P. R. China
§ School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418, P. R. China
∥ CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, P. R. China
⊥Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004, P. R. China
# Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
∇B.-B.Z., S.Y., J.-P.M., and Y.Z. contributed equally to this work.
J. Am. Chem. Soc.2019, 141, 15423--432
The presence of labile bulky insulating hydrocarbon ligands in halide perovskite nanocrystals (NCs) passivates surface traps but concurrently makes charge transport difficult in optoelectronic devices. Early efforts routinely rely on the replacement of long-chain ligands with short-chain cousins, leading to notable changes in NC’s sizes and photophysical properties and thus making it hard to obtain devices with nearly designed emissions. Here we report a general solution-phase ligand-exchange strategy to produce organic-ligand-lacking halide perovskite NCs with high photoluminescence (PL) quantum yields and good stability in ambient air. We demonstrate that the ligand exchange can be achieved by a well-controlled mild reaction of thionyl halide with the carboxylic and amine groups on the NC’s surface, resulting in nearly dry NCs with well-passivated surfaces and almost unaltered emission characteristics. Consequently, we achieve exceptionally high-performance blue perovskite NC lightemitting diodes (LEDs) with an external quantum efficiency of up to 1.35% and an extremely narrow full width at halfmaximum of 14.6 nm. Our work provides a systematic framework for preparing high-quality organic-ligand-lacking perovskite NC inks that can be directly cast as films featuring effective charge transport, thereby providing the foundation for further development of a wide range of efficient perovskite optoelectronic devices.