Unveiling the origin of performance reduction in perovskite solar cells with TiO2 electron transport layer: Conduction band minimum mismatches and chemical interactions at buried interface

Junkyeong Jeong, Donghee Kang, Do Hyung Chun, Dongguen Shin, Jong Hyeok Park, Sang Wan Cho, Kwangho Jeong, Hyunbok Lee, Yeonjin Yi

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Direct evidence of chemical interaction and origin of electron accumulation at a “buried” methylammonium lead triiodide (CH3NH3PbI3, hereafter “MAPI”)/TiO2 interface is presented in this study for the first time. Despite the high power conversion efficiency of perovskite solar cells (PSCs) using a TiO2 electron transport layer, the MAPI/TiO2 interface is believed as an electron accumulation position during device operation. To elucidate the cause of the electron accumulation, the energy level alignment at the MAPI/TiO2 interface should be understood. However, a buried MAPI/TiO2 interface forms after a thick MAPI layer deposition; thus, the electronic structure of the MAPI/TiO2 interface cannot be measured using surface-sensitive photoelectron spectroscopy in a conventional stack-up manner. In this study, we investigated the electronic structure of a buried MAPI/TiO2 interface by removing the MAPI and organic layers using solvent immersion. As a result, we reveal that a conduction band minimum (CBM) mismatch occurs owing to the Ti–O–Pb bonding on the TiO2 surface. The Ti–O–Pb bonds form by the Pb ions penetrating during the spin coating of the MAPI solution. When a [6,6]-phenyl C61 butyric acid methyl ester (PCBM) layer was inserted, the CBM mismatch was removed owing to the high work function of PCBM.

Original languageEnglish
Article number143490
JournalApplied Surface Science
Volume495
DOIs
Publication statusPublished - 2019 Nov 30

Fingerprint

Conduction bands
conduction bands
Butyric acid
solar cells
Electronic structure
Electrons
Esters
electrons
butyric acid
Spin coating
interactions
Photoelectron spectroscopy
Electron energy levels
Conversion efficiency
esters
Lead
electronic structure
Ions
submerging
coating

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

Cite this

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title = "Unveiling the origin of performance reduction in perovskite solar cells with TiO2 electron transport layer: Conduction band minimum mismatches and chemical interactions at buried interface",
abstract = "Direct evidence of chemical interaction and origin of electron accumulation at a “buried” methylammonium lead triiodide (CH3NH3PbI3, hereafter “MAPI”)/TiO2 interface is presented in this study for the first time. Despite the high power conversion efficiency of perovskite solar cells (PSCs) using a TiO2 electron transport layer, the MAPI/TiO2 interface is believed as an electron accumulation position during device operation. To elucidate the cause of the electron accumulation, the energy level alignment at the MAPI/TiO2 interface should be understood. However, a buried MAPI/TiO2 interface forms after a thick MAPI layer deposition; thus, the electronic structure of the MAPI/TiO2 interface cannot be measured using surface-sensitive photoelectron spectroscopy in a conventional stack-up manner. In this study, we investigated the electronic structure of a buried MAPI/TiO2 interface by removing the MAPI and organic layers using solvent immersion. As a result, we reveal that a conduction band minimum (CBM) mismatch occurs owing to the Ti–O–Pb bonding on the TiO2 surface. The Ti–O–Pb bonds form by the Pb ions penetrating during the spin coating of the MAPI solution. When a [6,6]-phenyl C61 butyric acid methyl ester (PCBM) layer was inserted, the CBM mismatch was removed owing to the high work function of PCBM.",
author = "Junkyeong Jeong and Donghee Kang and Chun, {Do Hyung} and Dongguen Shin and Park, {Jong Hyeok} and Cho, {Sang Wan} and Kwangho Jeong and Hyunbok Lee and Yeonjin Yi",
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T1 - Unveiling the origin of performance reduction in perovskite solar cells with TiO2 electron transport layer

T2 - Conduction band minimum mismatches and chemical interactions at buried interface

AU - Jeong, Junkyeong

AU - Kang, Donghee

AU - Chun, Do Hyung

AU - Shin, Dongguen

AU - Park, Jong Hyeok

AU - Cho, Sang Wan

AU - Jeong, Kwangho

AU - Lee, Hyunbok

AU - Yi, Yeonjin

PY - 2019/11/30

Y1 - 2019/11/30

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