Understanding the Morphology of High-Performance Solar Cells Based on a Low-Cost Polymer Donor

Zhengqing Xu; Fei Pan; Chenkai Sun; Song Hong; Shanshan Chen; Changduk Yang; Zhiguo Zhang; Yao Liu; Thomas P Russell; Yongfang Li; Dong Wang

doi:10.1021/acsami.9b22666

Understanding the Morphology of High-Performance Solar Cells Based on a Low-Cost Polymer Donor

ACS Appl Mater Interfaces. 2020 Feb 26;12(8):9537-9544. doi: 10.1021/acsami.9b22666. Epub 2020 Feb 14.

Authors

Zhengqing Xu¹, Fei Pan^{2

3}, Chenkai Sun^{2

3}, Song Hong¹, Shanshan Chen^{4

5}, Changduk Yang⁵, Zhiguo Zhang^{2

3}, Yao Liu¹, Thomas P Russell^{1

6

7}, Yongfang Li^{2

3}, Dong Wang¹

Affiliations

¹ Beijing Advanced Innovation Center for Soft Matter Science and Engineering & State Key Laboratory of Organic-Inorganic Composites , Beijing University of Chemical Technology , Beijing 100029 , China.
² Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China.
³ School of Chemical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , China.
⁴ MOE Key Laboratory of Low-grade Energy Utilization Technologies and Systems, CQU-NUS Renewable Energy Materials & Devices Joint Laboratory, School of Energy & Power Engineering , Chongqing University , Chongqing 400044 , China.
⁵ Department of Energy Engineering, School of Energy and Chemical Engineering, Low Dimensional Carbon Materials Center , Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798 , South Korea.
⁶ Polymer Science and Engineering Department , University of Massachusetts Amherst , Massachusetts 01003 , United States.
⁷ Materials Sciences Division , Lawrence Berkeley National Laboratory , 1 Cyclotron Road , Berkeley , California 94720 , United States.

PMID: 32013381
DOI: 10.1021/acsami.9b22666

Abstract

A low-cost and high-performance bulk heterojunction (BHJ) solar cell comprising an emerging polymer donor, poly[(thiophene)-alt-(6,7-difluoro-2-(2-hexyldecyloxy)quinoxaline)] (PTQ10), shows an efficiency of 12.7%. To improve the performance of the solar cells, a better understanding of the structure-property relationships of the PTQ10-based devices is crucial. Here, we fabricate PTQ10/nonfullerene and fullerene BHJ devices, including PTQ10/IDIC, PTQ10/ITIC, and PTQ10/PC₇₁BM, processed with or without thermal annealing and additive and provide detailed descriptions of the relationships between the morphology and performance. PTQ10 is found to be highly miscible with nonfullerene IDIC and ITIC acceptors and poorly miscible with fullerene PC₇₁BM acceptors. Thermal annealing promotes the crystallization of PTQ10 and phase separation of all PTQ10/IDIC, PTQ10/ITIC, and PTQ10/PC₇₁BM devices, leading to an increased power conversion efficiencies (PCEs) of the PTQ10/IDIC and PTQ10/ITIC devices but a decreased PCE of PTQ10/PC₇₁BM devices with 1,8-di-iodooctane (DIO) additive. Without thermal annealing, DIO greatly improves the morphology of PTQ10/PC₇₁BM, leading to a higher PCE. The results show that the degree of phase separation and ordering in the PTQ10-based devices significantly influences device performance. The morphology-property correlations demonstrated will assist in the rational design of these low-cost polymer donor-based solar cells to achieve even higher performance.

Keywords: crystallization; miscibility; morphology; phase separation; polymer solar cells.