Highly Efficient Ternary-Blend Polymer Solar Cells Enabled by a Nonfullerene Acceptor and Two Polymer Donors with a Broad Composition Tolerance

Xiaopeng Xu; Zhaozhao Bi; Wei Ma; Zishuai Wang; Wallace C H Choy; Wenlin Wu; Guangjun Zhang; Ying Li; Qiang Peng

doi:10.1002/adma.201704271

Highly Efficient Ternary-Blend Polymer Solar Cells Enabled by a Nonfullerene Acceptor and Two Polymer Donors with a Broad Composition Tolerance

Adv Mater. 2017 Dec;29(46). doi: 10.1002/adma.201704271. Epub 2017 Oct 16.

Authors

Xiaopeng Xu¹, Zhaozhao Bi², Wei Ma², Zishuai Wang³, Wallace C H Choy³, Wenlin Wu¹, Guangjun Zhang¹, Ying Li¹, Qiang Peng¹

Affiliations

¹ Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, and State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610064, P. R. China.
² State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
³ Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong 999077, P. R. China.

PMID: 29044740
DOI: 10.1002/adma.201704271

Abstract

In this work, highly efficient ternary-blend organic solar cells (TB-OSCs) are reported based on a low-bandgap copolymer of PTB7-Th, a medium-bandgap copolymer of PBDB-T, and a wide-bandgap small molecule of SFBRCN. The ternary-blend layer exhibits a good complementary absorption in the range of 300-800 nm, in which PTB7-Th and PBDB-T have excellent miscibility with each other and a desirable phase separation with SFBRCN. In such devices, there exist multiple energy transfer pathways from PBDB-T to PTB7-Th, and from SFBRCN to the above two polymer donors. The hole-back transfer from PTB7-Th to PBDB-T and multiple electron transfers between the acceptor and the donor materials are also observed for elevating the whole device performance. After systematically optimizing the weight ratio of PBDB-T:PTB7-Th:SFBRCN, a champion power conversion efficiency (PCE) of 12.27% is finally achieved with an open-circuit voltage (V_oc ) of 0.93 V, a short-circuit current density (J_sc ) of 17.86 mA cm^-2 , and a fill factor of 73.9%, which is the highest value for the ternary OSCs reported so far. Importantly, the TB-OSCs exhibit a broad composition tolerance with a high PCE over 10% throughout the whole blend ratios.

Keywords: broad composition tolerance; charge transfer; energy transfer; nonfullerene acceptors; ternary blend polymer solar cells.