Title: Synergy of Liquid-Crystalline Small-Molecule and Polymeric Donors Delivers Uncommon Morphology Evolution and 16.6% Efficiency Organic Photovoltaics

Abstract

Achieving an ideal morphology is an imperative avenue for enhancing key parameters toward high-performing organic solar cells (OSCs). Among a myriad of morphological-control methods, the strategy of incorporating a third component with structural similarity and crystallinity difference to construct ternary OSCs has emerged as an effective approach to regulate morphology. A nematic liquid-crystalline benzodithiophene terthiophene rhodamine (BTR) molecule, which possesses the same alkylthio-thienyl-substituted benzo moiety but obviously stronger crystallinity compared to classical medium-bandgap polymeric donor PM6, is employed as a third component to construct ternary OSCs based on a PM6:BTR:Y6 system. The doping of BTR (5 wt%) is found to be enough to improve the OSC morphology—significantly enhancing the crystallinity of the photoactive layer while slightly reducing the donor/acceptor phase separation scale simultaneously. Rarely is such a morphology evolution reported. It positively affects the electronic properties of the device—prolongs the carrier lifetime, shortens the photocurrent decay time, facilitates exciton dissociation, charge transport, and collection, and ultimately boosts the power conversion efficiency from 15.7% to 16.6%. This result demonstrates that the successful synergy of liquid-crystalline small-molecule and polymeric donors delicately adjusts the active-layer morphology and refines device performance, which brings vibrancy to the OSC research field.

Authors:

Yan, Cenqi ^[1]; Tang, Hua ^[2]; Ma, Ruijie ^[3]; Zhang, Ming ^[4]; Liu, Tao ^[5]; Lv, Jie ^[6]; Huang, Jiaming ^[1]; Yang, YanKang ^[4]; Xu, Tongle ^[6]; Kan, Zhipeng ^[6]; Yan, He ^[5]; Liu, Feng ^[4]; Lu, Shirong ^[6]; Li, Gang  ^[1]

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+ Show Author Affiliations

1. The Hong Kong Polytechnic Univ. Shenzhen (China). ShenZhen Research Inst.; The Hong Kong Polytechnic Univ., Hung Hum Kowloon, Hong Kong (China). Dept. of Electronic and Information Engineering
2. The Hong Kong Polytechnic Univ. Shenzhen (China). ShenZhen Research Inst.; The Hong Kong Polytechnic Univ., Hung Hum Kowloon, Hong Kong (China). Dept. of Electronic and Information Engineering; Chongqing Inst. of Green and Intelligent Technology, Chongqing (China). Organic Semiconductor Research Center
3. Hong Kong Univ. of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong (China). Center for Tissue Restoration & Reconstruction. Hong Kong Branch of Chinese National Engineering Research. Dept. of Chemistry
4. Shanghai Jiaotong Univ., Shanghai (China). Collaborative Innovation Center of IFSA (CICIFSA). Dept. of Physics and Astronomy
5. Hong Kong Univ. of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong (China). Center for Tissue Restoration & Reconstruction. Hong Kong Branch of Chinese National Engineering Research. Dept. of Chemistry
6. Chongqing Inst. of Green and Intelligent Technology, Chongqing (China). Organic Semiconductor Research Center

Publication Date:

Thu Jun 18 00:00:00 EDT 2020

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1816503

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Advanced Science

Additional Journal Information:

Journal Volume: 7; Journal Issue: 15; Journal ID: ISSN 2198-3844

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; liquid-crystalline molecules; morphology; organic solar cells; ternary structures