High Mobility Indium Oxide Electron Transport Layer for an Efficient Charge Extraction and Optimized Nanomorphology in Organic Photovoltaics

Wenchao Huang; Bowen Zhu; Sheng-Yung Chang; Shuanglin Zhu; Pei Cheng; Yao-Tsung Hsieh; Lei Meng; Rui Wang; Chaochen Wang; Chenhui Zhu; Christopher McNeill; Mingkui Wang; Yang Yang

doi:10.1021/acs.nanolett.8b02452

High Mobility Indium Oxide Electron Transport Layer for an Efficient Charge Extraction and Optimized Nanomorphology in Organic Photovoltaics

Nano Lett. 2018 Sep 12;18(9):5805-5811. doi: 10.1021/acs.nanolett.8b02452. Epub 2018 Aug 10.

Authors

Wenchao Huang^{1

2}, Bowen Zhu^{1

2}, Sheng-Yung Chang^{1

2}, Shuanglin Zhu^{1

2}, Pei Cheng^{1

2}, Yao-Tsung Hsieh^{1

2}, Lei Meng^{1

2}, Rui Wang^{1

2}, Chaochen Wang^{1

2}, Chenhui Zhu³, Christopher McNeill⁴, Mingkui Wang⁵, Yang Yang^{1

2}

Affiliations

¹ Department of Materials Science and Engineering , University of California , Los Angeles , California 90095 , United States.
² California NanoSystems Institute , University of California , Los Angeles , California 90095 , United States.
³ Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
⁴ Department of Materials Science and Engineering , Monash University , Clayton , Victoria 3800 , Australia.
⁵ Wuhan National Laboratory for Optoelectronics , Huazhong University of Science and Technology , Wuhan 430070 , People's Republic of China.

PMID: 30075074
DOI: 10.1021/acs.nanolett.8b02452

Abstract

The electron transport layer (ETL) plays an important role in determining the device efficiency of organic solar cells (OSCs). A rational design of an ETL for OSCs targets high charge extraction and induction of an optimized active layer morphology. In this Letter, a high mobility In₂O₃ synthesized via a solution-processed combustion reaction is successfully used as a universal ETL in an organic photovoltaic device. With the modification of a thin layer of polyethylenimine ethoxylated (PEIE), a device based on crystalline In₂O₃ outperforms its counterpart, ZnO, in both PBDTTT-EFT-based fullerene and nonfullerene systems. As ZnO is replaced by In₂O₃, the average efficiency increases from 9.5% to 10.5% for PBDTTT-EFT-PC₇₁BM fullerene-based organic solar cells and also increases from 10.8% to 11.5% for PBDTTT-EFT-IEICO-4F nonfullerene-based organic solar cells, respectively. Morphological studies have unraveled the fact that the crystalline In₂O₃ ETL with highly aligned nanocrystallites has induced the crystallization of polymer into a preferential molecular packing that favors the charge transport across an active layer. From the photophysical study, it is found that charge extraction in the crystalline In₂O₃ device is significantly faster than in the ZnO device due to the higher mobility of In₂O₃ and optimized nanomorphology of the active layer.

Keywords: Organic solar cells; charge extraction; electron transport layer; indium oxide; morphology.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't