Imbedded Nanocrystals of CsPbBr3 in Cs4 PbBr6 : Kinetics, Enhanced Oscillator Strength, and Application in Light-Emitting Diodes

Junwei Xu; Wenxiao Huang; Peiyun Li; Drew R Onken; Chaochao Dun; Yang Guo; Kamil B Ucer; Chang Lu; Hongzhi Wang; Scott M Geyer; Richard T Williams; David L Carroll

doi:10.1002/adma.201703703

Imbedded Nanocrystals of CsPbBr₃ in Cs₄ PbBr₆ : Kinetics, Enhanced Oscillator Strength, and Application in Light-Emitting Diodes

Adv Mater. 2017 Nov;29(43). doi: 10.1002/adma.201703703. Epub 2017 Oct 10.

Authors

Junwei Xu^{1

2}, Wenxiao Huang^{1

2}, Peiyun Li², Drew R Onken², Chaochao Dun^{1

2}, Yang Guo^{1

3

4}, Kamil B Ucer², Chang Lu⁵, Hongzhi Wang^{3

4}, Scott M Geyer⁵, Richard T Williams^{1

2}, David L Carroll^{1

2}

Affiliations

¹ Center for Nanotechnology and Molecular Materials, Wake Forest University, Winston-Salem, NC, 27109, USA.
² Department of Physics, Wake Forest University, Winston-Salem, NC, 27106, USA.
³ State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai, 201620, P. R. China.
⁴ College of Materials Science and Engineering, Donghua University, Shanghai, 201620, P. R. China.
⁵ Department of Chemistry, Wake Forest University, Winston-Salem, NC, 27106, USA.

PMID: 29024076
DOI: 10.1002/adma.201703703

Abstract

Solution-grown films of CsPbBr₃ nanocrystals imbedded in Cs₄ PbBr₆ are incorporated as the recombination layer in light-emitting diode (LED) structures. The kinetics at high carrier density of pure (extended) CsPbBr₃ and the nanoinclusion composite are measured and analyzed, indicating second-order kinetics in extended and mainly first-order kinetics in the confined CsPbBr₃ , respectively. Analysis of absorption strength of this all-perovskite, all-inorganic imbedded nanocrystal composite relative to pure CsPbBr₃ indicates enhanced oscillator strength consistent with earlier published attribution of the sub-nanosecond exciton radiative lifetime in nanoprecipitates of CsPbBr₃ in melt-grown CsBr host crystals and CsPbBr₃ evaporated films.

Keywords: excitonic kinetics; lead halide perovskites; light-emitting diodes; nanoinclusions; oscillator strength.