All-solution-processed flexible semitransparent organic solar cells based on sprayed silver nanowire composites as top electrodes

Solution processable transparent top electrodes with good conductivity and high transmittance play a critical role in developing highly efficient semitransparent organic solar cells (ST-OSCs). Herein, a simple low-temperature spray-coating method is proposed to fabricate silver nanowires/zinc oxide nanoparticles (AgNWs/ZnO) composite electrodes. The effects of coverage of ZnO nanoparticles on optoelectronic properties and surface morphologies of the composites are systemically investigated. Compared to the pristine AgNWs, the AgNWs/ZnO composite layer exhibits improved electrical conductivity due to the filling of nanoparticles as well as the capillary force caused during the volatilization of ZnO dispersion. A low sheet resistance of 8.3 Ω/ and a high transmittance of 78.91 % at 550 nm are achieved in the optimized AgNWs/ZnO composite films with excellent thermal and mechanical stabilities. By using the spray-coated AgNWs composite as the top electrode, the PM6:N3 based ST-OSCs prepared on ITO/glass substrate attain a power conversion efficiency (PCE) of 10.88 % and an average transmittance (AVT) of 28.80 % due to the enhanced charge extraction and suppressed trap-assisted recombination. Moreover, fully solution-processed ST-OSCs are fabricated based on AgNWs/ZnO top electrodes, achieving a PCE of 9.01 % and an AVT of 27.8 %. It provides a simple and effective strategy to fabricate transparent flexible top electrodes and may pave the way towards all-solution-processed highly efficient ST-OSCs.