Molecular Order Control of Non-fullerene Acceptors for High-Efficiency Polymer Solar Cells

By Mengxue Chen, Jinlong Cai, Emma L. K. Spooner, Huijun Zhang, Robert S. Gurney, Danjie Liu, Zuo Xiao, David G Lidzey, Liming Ding, Tao Wang. Joule, 2019

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Summary Adjusting molecular ordering, orientation, and nanoscale morphology within the photoactive layer of polymer:non-fullerene organic solar cells is crucial in achieving high power-conversion efficiency (PCE). Herein, we demonstrate that the molecular ordering and orientation of the n-type small-molecule acceptor COi8DFIC can be tuned from flat-on and edge-on lamellar crystalline to H- and J-type π-π stacking during the solution-casting process, resulting in broadened photon absorption and fine phase separation with the electron donor PTB7-Th. This favorable morphology with face-on π-π stacked electron donors and acceptors promotes efficient exciton dissociation at the donor/acceptor interface, together with enhanced and balanced carrier mobility. The enhanced short-circuit current density and fill factor lead to the achievement of a maximum PCE of 13.8% in binary, single-junction PTB7-Th:COi8DFIC non-fullerene polymer solar cells while also exhibiting superior stability.

Subfields: Electrical and Electronic Engineering, Polymers and Plastics

View Paper: https://www.semanticscholar.org/paper/ff2d866b70b60a7ac0c8339e35d8d25bef144bc6