Efficient Inverted Solar Cells Using Benzotriazole-Based Small Molecule and Polymers

Ja Eun Lee; Yoon Kim; Yang Ho Na; Nam Seob Baek; Jae Woong Jung; Yura Choi; Namchul Cho; Tae-Dong Kim

doi:10.3390/polym13030393

Efficient Inverted Solar Cells Using Benzotriazole-Based Small Molecule and Polymers

Polymers (Basel). 2021 Jan 27;13(3):393. doi: 10.3390/polym13030393.

Authors

Ja Eun Lee¹, Yoon Kim¹, Yang Ho Na¹, Nam Seob Baek², Jae Woong Jung³, Yura Choi⁴, Namchul Cho⁴, Tae-Dong Kim¹

Affiliations

¹ Department of Advanced Materials, Hannam University, Daejeon 34054, Korea.
² ChemOptics, Daejeon 34026, Korea.
³ Advanced Materials Engineering for Information and Electronics, Kyung Hee University, Youngin 17104, Korea.
⁴ Department of Energy Systems Engineering, Soonchunhyang University, Asan 31538, Korea.

Abstract

We synthesized medium-band-gap donor-acceptor (D-A) -type conjugated polymers (PBTZCZ-L and PBTZCZ-H) consisting of a benzotriazole building block as an acceptor and a carbazole unit as a donor. In comparison with the polymers, a small conjugated molecule (BTZCZ-2) was developed, and its structural, thermal, optical, and photovoltaic properties were investigated. The power conversion efficiency (PCE) of the BTZCZ-2-based solar cell devices was less than 0.5%, considerably lower than those of polymer-based devices with conventional device structures. However, inverted solar cell devices configured with glass/ITO/ZnO:PEIE/BTZCZ-2:PC₇₁BM/MoO₃/Ag showed a tremendously improved efficiency (PCE: 5.05%, J_sc: 9.95 mA/cm², V_oc: 0.89 V, and FF: 57.0%). We believe that this is attributed to high energy transfer and excellent film morphologies.

Keywords: benzotriazole; molecular aggregation; morphology; polymer solar cells; small-molecule solar cells.