Enhancement of 3D/2D perovskite solar cells using an F4TCNQ molecular additive

Jingsong Sun, Naresh Chandrasekaran, Chang Liu, Andrew D. Scully, Wenping Yin, Chun Kiu Ng, Jacek J. Jasieniak

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Recent developments in hybrid organic-inorganic lead halide perovskite solar cells (PSCs) have shown that use of a 2-dimensional (2D) perovskite capping layer on a 3D perovskite absorber layer (3D/2D PSCs) results in substantially improved environmental stability of the devices. However, in these 3D/2D PSC structures the poor charge transporting properties through the 2D layer hinder device performance, particularly for thicker 2D layers. Here, we report a facile method that overcomes some of the inherent challenges in using such 2D capping layers through the introduction of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) as a molecular additive into the 2D layer. It is found that this additive undergoes partial charge transfer with the perovskite layer to provide a passivation effect, which also modifies the crystalline domain sizes of the 2D perovskite. PSCs incorporating a F4TCNQ-modified 2D capping layer grown in situ on top of the 3D Cs/MA/FA mixed-cation perovskite absorber layer display modified interfacial characteristics that yield improved charge extraction and reduced charge recombination compared with 3D/2D PSCs comprising an unmodified 2D capping layer. This modification results in 3D/2D PSCs for which the maximum power conversion efficiency is increased to more than 20% compared with 18.2% for unmodified 2D capping layers.

Original languageEnglish
Pages (from-to)8205-8215
Number of pages11
JournalACS Applied Energy Materials
Volume3
Issue number9
DOIs
Publication statusPublished - 28 Sep 2020

Keywords

  • 2D perovskite
  • charge transport layer
  • F4TCNQ
  • perovskite solar cell
  • stability

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