High Color Purity Lead-Free Perovskite Light-Emitting Diodes via Sn Stabilization

Hongyan Liang, Fanglong Yuan, Andrew Johnston, Congcong Gao, Hitarth Choubisa, Yuan Gao, Ya Kun Wang, Laxmi Kishore Sagar, Bin Sun, Peicheng Li, Golam Bappi, Bin Chen, Jun Li, Yunkun Wang, Yitong Dong, Dongxin Ma, Yunan Gao, Yongchang Liu, Mingjian Yuan, Makhsud I. SaidaminovSjoerd Hoogland, Zheng Hong Lu*, Edward H. Sargent

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

151 Scopus citations

Abstract

Perovskite-based light-emitting diodes (PeLEDs) are now approaching the upper limits of external quantum efficiency (EQE); however, their application is currently limited by reliance on lead and by inadequate color purity. The Rec. 2020 requires Commission Internationale de l'Eclairage coordinates of (0.708, 0.292) for red emitters, but present-day perovskite devices only achieve (0.71, 0.28). Here, lead-free PeLEDs are reported with color coordinates of (0.706, 0.294)—the highest purity reported among red PeLEDs. The variation of the emission spectrum is also evaluated as a function of temperature and applied potential, finding that emission redshifts by <3 nm under low temperature and by <0.3 nm V−1 with operating voltage. The prominent oxidation pathway of Sn is identified and this is suppressed with the aid of H3PO2. This strategy prevents the oxidation of the constituent precursors, through both its moderate reducing properties and through its forming complexes with the perovskite that increase the energetic barrier toward Sn oxidation. The H3PO2 additionally seeds crystal growth during film formation, improving film quality. PeLEDs are reported with an EQE of 0.3% and a brightness of 70 cd m−2; this is the record among reported red-emitting, lead-free PeLEDs.

Original languageEnglish (US)
Article number1903213
JournalAdvanced Science
Volume7
Issue number8
DOIs
StatePublished - Apr 1 2020

Keywords

  • HPO additives
  • Sn stabilization
  • Sn-based red light-emitting diodes
  • antioxidation
  • lead-free perovskites

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • General Chemical Engineering
  • General Materials Science
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)
  • General Engineering
  • General Physics and Astronomy

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