Guanidinium-Pseudohalide Perovskite Interfaces Enable Surface Reconstruction of Colloidal Quantum Dots for Efficient and Stable Photovoltaics

Jonghee Yang, Seong Chan Cho, Seungjin Lee, Jung Won Yoon, Woo Hyeon Jeong, Hochan Song, Jae Taek Oh, Seul Gi Lim, Sung Yong Bae, Bo Ram Lee, Mahshid Ahmadi, Edward H. Sargent, Whikun Yi, Sang Uck Lee*, Hyosung Choi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Complete surface passivation of colloidal quantum dots (CQDs) and their strong electronic coupling are key factors toward high-performance CQD-based photovoltaics (CQDPVs). Also, the CQD matrices must be protected from oxidative environments, such as ambient air and moisture, to guarantee air-stable operation of the CQDPVs. Herein, we devise a complementary and effective approach to reconstruct the oxidized CQD surface using guanidinium and pseudohalide. Unlike conventional halides, thiocyanate anions provide better surface passivation with effective replacement of surface oxygen species and additional filling of defective sites, whereas guanidinium cations promote the construction of epitaxial perovskite bridges within the CQD matrix and augment electronic coupling. Additionally, we replace a defective 1,2-ethanedithiol-treated CQD hole transport layer (HTL) with robust polymeric HTLs, based on a judicious consideration of the energy level alignment established at the CQD/HTL interface. These efforts collectively result in high-performance and stable CQDPVs with photocurrents over 30 mA cm-2, ∼80% quantum efficiency at excitonic peaks and stable operation under humid and ambient conditions. Elucidation of carrier dynamics further reveals that interfacial recombination associated with band alignment governs both the CQDPV performance and stability.

Original languageEnglish (US)
Pages (from-to)1649-1660
Number of pages12
JournalACS nano
Volume16
Issue number1
DOIs
StatePublished - Jan 25 2022

Keywords

  • Colloidal Quantum Dots
  • Guanidinium
  • Perovskites
  • Photovoltaics
  • Pseudohalides

ASJC Scopus subject areas

  • General Engineering
  • General Physics and Astronomy
  • General Materials Science

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