Chloride Passivation of ZnO Electrodes Improves Charge Extraction in Colloidal Quantum Dot Photovoltaics

Jongmin Choi, Younghoon Kim, Jea Woong Jo, Junghwan Kim, Bin Sun, Grant Walters, F. Pelayo García de Arquer, Rafael Quintero-Bermudez, Yiying Li, Chih-Shan Tan, Li Na Quan, Andrew Pak Tao Kam, Sjoerd Hoogland, Zhenghong Lu, Oleksandr Voznyy*, Edward H. Sargent*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

76 Scopus citations

Abstract

The tunable bandgap of colloidal quantum dots (CQDs) makes them an attractive material for photovoltaics (PV). The best present-day CQD PV devices employ zinc oxide (ZnO) as an electron transport layer; however, it is found herein that ZnO's surface defect sites and unfavorable electrical band alignment prevent devices from realizing their full potential. Here, chloride (Cl)-passivated ZnO generated from a solution of presynthesized ZnO nanoparticles treated using an organic-solvent-soluble Cl salt is reported. These new ZnO electrodes exhibit decreased surface trap densities and a favorable electronic band alignment, improving charge extraction from the CQD layer and achieving the best-cell power conversion efficiency (PCE) of 11.6% and an average PCE of 11.4 ± 0.2%.
Original languageEnglish
JournalAdvanced Materials
Volume29
Issue number33
DOIs
StatePublished - 6 Sep 2017

Keywords

  • ZnO
  • band alignment
  • passivation
  • quantum-dot solar cells

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