Stable and Strong Emission CsPbBr3 Quantum Dots by Surface Engineering for High-Performance Optoelectronic Films

Chao Zheng; Chenghao Bi; Fan Huang; David Binks; Jianjun Tian

doi:10.1021/acsami.9b07818

Stable and Strong Emission CsPbBr₃ Quantum Dots by Surface Engineering for High-Performance Optoelectronic Films

ACS Appl Mater Interfaces. 2019 Jul 17;11(28):25410-25416. doi: 10.1021/acsami.9b07818. Epub 2019 Jul 5.

Authors

Chao Zheng¹, Chenghao Bi¹, Fan Huang¹, David Binks², Jianjun Tian¹

Affiliations

¹ Institute for Advanced Materials and Technology , University of Science and Technology Beijing , Beijing 100083 , China.
² School of Physics and Astronomy and Photon Science Institute , University of Manchester , Manchester M13 9PL , U.K.

PMID: 31276360
DOI: 10.1021/acsami.9b07818

Abstract

We demonstrated complete surface passivation of CsPbBr₃ quantum dots (QDs) by treatment with di-dodecyldimethylammonium bromide (DDAB) and sodium thiocyanate (NaSCN), resulting in dispersions with photostable photoluminescence of near-unity quantum yield (∼100%) as well as high carrier mobility of QDs' film. Br^- from DDAB and SCN^- from NaSCN passivated the bromine vacancies of the QDs to reduce the surface defect density and increase the stability. The QDs-passivated maintained the original photoluminescence intensity under ultraviolet irradiation from a 150 W xenon lamp for 1 h, whereas the PL intensity of QDs-control dropped quickly to 20% of its initial value. The shorter DDA⁺ ligands also improved carrier transport in the QDs-passivated film, which was verified by conductivity and space charge limited current measurements. When used as the photoemitting species in a solution-processed light-emitting diode structure, the surface treatment increased the maximum luminance from 550 to 1200 cd·m^-2 and reduced the turn-on voltage from 3.1 to 2.8 V.

Keywords: inorganic perovskite; optoelectronics; passivation; quantum dots; surface engineering.