Boosted Efficiency Over 18.1% of Polymer Solar Cells by Employing Large Extinction Coefficients Material as the Third Component

• Published in: Macromolecular rapid communications. 2022-08, Vol.43 (15), p.e2200345-n/a
• Main Authors: Zhang, Shuping, Ma, Xiaoling, Xu, Chunyu, Xu, Wenjing, Jeong, Sang Young, Woo, Han Young, Zhou, Zhengji, Zhang, Xiaoli, Zhang, Fujun
• Format: Article
• Language: English
• Subjects: Bouguer law; Circuits; Energy conversion efficiency; Excitons; Matrix methods; morphology regulators; photogenerated exciton distribution; Photons; Photovoltaic cells; polymer solar cells; Polymers; power conversion efficiency; Refractivity; Short circuit currents; Short-circuit current; Solar cells; ternary strategies; Wavelength
• ISSN: 1022-1336; 1521-3927
• DOI: 10.1002/marc.202200345

A series of binary and ternary polymer solar cells (PSCs) is successfully fabricated. The optimal ternary PSCs achieve a power conversion efficiency (PCE) of 18.14%, benefiting from the increased short circuit current density (JSC) of 26.53 mA cm−2 and fill factor (FF) of 78.51% in comparison with the JSCs (25.05 mA cm−2 and 25.65 mA cm−2) and the FFs (77.13% and 76.55%) of the corresponding binary PSCs. The photon harvesting ability of ternary active layers can be enhanced, which can be confirmed from the EQE spectral difference of the optimized ternary and binary PSCs, especially in the wavelength range from 680 nm to 800 nm. The refractive index and extinction coefficients of binary and ternary blend films are measured, which can well support the enhanced photon harvesting ability in different wavelength ranges. Photogenerated exciton distribution in active layers is simulated by the transmission matrix method based on the Beer–Lambert law. The photogenerated exciton density can be enhanced in the middle of the active layers by incorporating a third component in acceptors, which is conducive to charge collection by individual electrodes, resulting in the simultaneously enhanced JSC and FF of the optimal ternary PSCs. Ternary polymer solar cells (PSCs) are fabricated with polymer PM6 as donor and m‐BTP‐PhC6 and Y6 as acceptors. The incorporation of Y6 can effectively enhance photon harvesting in long wavelength range, optimize phase separation, and adjust photogenerated exciton distribution in the ternary active layers, leading to the PCE enhancement from 16.81% to 18.12%.