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Using narrow bandgap nonfullerene acceptors (NFAs) can broaden the absorption spectrum of organic solar cells (OSCs) to the near‐infrared region. However, the simultaneously decreased extinction coefficient of the active layer at the blue region results in inevitable light escaping and energy loss. Herein, a blazed grating‐based device configuration consisting of a patterned rear electrode is employed to compensate for the low absorption of nonfullerene OSCs. Experimental results reveal that the normal incidence light, especially blue light, that bounces off the patterned rear electrode is concentrated in a large tilted angle and subsequently trapped in waveguide mode. Along with the excitation of surface plasmon polariton, the structured nonfullerene OSCs using a new‐designed PM6:M36 active layer obtain the broadband absorption enhancement with 1.5 times increase at the blue region. The optimized device achieves an 8.95% increase in photocurrent and a champion power conversion efficiency of approaching 18%, which is the highest reported value among all the devices based on A‐D‐A type NFAs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A transparent electrode architecture with silver nanowires is proposed. • Surface plasmon polaritons of AgNWs are remitted via non-radiative damping. • The boosted radiative energy transfer causes a broadband increase in optical transmittance. • Flexible organic photovoltaics obtain a power conversion efficiency of 18.1%. The light extinction caused by plasmonic effects is the bottleneck of developing the highly transparent silver nanowires (AgNWs)-based electrode in the applications of flexible organic photovoltaics. Here, a new electrode architecture is proposed to remit the surface plasmon polaritons (SPPs) of AgNWs through hot-nanoimprint introduced lateral buds, which can couple SPPs to radiation via non-radiative damping and thus reduce the plasmonic energy loss. The boosted radiative energy transfer generates a broadband increase in optical transmittance of AgNWs, yielding the highest value of 91.2% and an average one of 87.56%. Due to the synergetic effect of plasmon out-coupling, anti-reflection, and morphological improvement of the deformed AgNWs electrode, flexible organic photovoltaics obtain an 8.7% increase in power conversion efficiency as compared to their counterpart, achieving a state-of-the-art efficiency of 18.1%. [ABSTRACT FROM AUTHOR]

• Lateral charge collection range of silver nanowires are clarified via microscopic photocurrent images. • Doping LiTFSI in ZnO improves carrier mobility and energy level alignment with AgNWs. • Flexible organic solar cells achieve an efficiency of 18.0%. Although the transparency and sheet resistance of silver nanowire (AgNW) electrodes are comparable to those of rigid indium-tin-oxide electrodes, flexible organic solar cells (FOSCs) are still less efficient than their rigid counterparts. Herein, by recording the microscopic photocurrent images of AgNW-based FOSCs in operation, it has been revealed that the limited lateral charge collection range of AgNW leads to inevitable electrical energy loss. The regulation of carrier mobility and energy level of adjacent ZnO electron transport layer increases the effective collection range of AgNWs by 1.8 times and uniform the electrical potential distribution in FOSCs. The D18:Y6:PC 71 BM-based FOSCs achieve a power conversion efficiency of approaching 18%. Moreover, the performance drop of large-area FOSCs is significantly reduced due to the improved charge collection on large area scale. This work provides an intuitive insight into the electrical energy loss mechanism of AgNW electrodes and demonstrates an electric field regulation strategy in FOSCs. [ABSTRACT FROM AUTHOR]