Enhanced stability and photovoltage for inverted perovskite solar cells via precursor engineering

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Changwen Liu
  • Weiguang Kong
  • Wang Li
  • Hong Chen
  • Dedi Li
  • Weijun Wang
  • Baomin Xu
  • Chun Cheng

Detail(s)

Original languageEnglish
Pages (from-to)15880-15886
Journal / PublicationJournal of Materials Chemistry A
Volume7
Issue number26
Online published4 Jun 2019
Publication statusPublished - 14 Jul 2019

Abstract

We report on a method of precursor engineering to prepare high quality and stable perovskites based on formamidinium/methylammonium (FAMA) mixed-cations. CsI is commonly used to inhibit the photoinactive phase in FAMA perovskites. However, the hydrophilic nature of CsI would result in a structural instability issue at high relative humidity (RH). Besides, in inverted perovskite solar cells (PSCs) based on organic hole transport layers, the low conduction band minimum (CBM) of FAMA perovskites would lead to small open circuit voltage (Voc) (∼1.0 V), and thus additional surface passivation/modification layers are normally employed, indicating that it is essential to improve the basic precursors for high quality perovskite films. Herein, the proposed method is realized via ternary precursor alloying which endows the perovskite with increased grain size, enhanced crystallinity, reduced trap states, and a pure photoactive phase without the assistance of CsI. Without passivation/modification layers, the device Voc is enhanced markedly from 1.0 V to 1.1 V on average, and a champion power conversion efficiency of 20.7% with negligible hysteresis is achieved. Moreover, as they are free of hydrophilic CsI, both the photoactive perovskite films and devices exhibit excellent stability in ambient air. At high RH (70%), the optimized device without encapsulation only loses 16% of its efficiency after 1000 h storage, indicating the potential for the development of efficient and stable PSCs.

Citation Format(s)

Enhanced stability and photovoltage for inverted perovskite solar cells via precursor engineering. / Liu, Changwen; Kong, Weiguang; Li, Wang; Chen, Hong; Li, Dedi; Wang, Weijun; Xu, Baomin; Cheng, Chun; Jen, Alex K.Y.

In: Journal of Materials Chemistry A, Vol. 7, No. 26, 14.07.2019, p. 15880-15886.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review