Plasmonic nanocavity organic solar cells with highly enhanced power conversion efficiency, broad-band, and omni-acceptance

We report further experimental study and demonstration of the new ultra-thin high-efficiency organic solar cell (SC) structure, termed “plasmonic cavity with subwavelength hole-array (PlaCSH) solar cell”. A PlaCSH-SC comprises a 30 nm thick transparent metal-mesh electrode with subwavelength hole-array (MESH), a metal back electrode, and in-between a polymer photovoltaic active layer of 60-85 nm thick. The PlaCSH structure was implemented into three different types of PV active material systems (P3HT/PCBM, PCDTBT/PCBM, and PTB7/PCBM), and all of them achieved an average light absorptance over 90%, a broad-band (>500nm), and a omni acceptance (the acceptance nearly independent of light incident angle and polarization); leading to photo-current (Jsc) and standard-solar-irradiation power conversion efficiency (PCE) of 21-41% and 17-52%, respectively, higher than the reference ITO-SC (the same structure except the MESH of PlaCSH-SC replaced by ITO). In PlaCSH-SCs, the PCDTBT/PCBM gives the highest Voc (0.86V) and PTB7/PCBM gives the highest Jsc (15.6mA/cm²). These findings further demonstrate that PlaCSH is a universal structure that can enhance solar cell performances in a broad range of active materials, and should be applicable to thin solar cells in many other materials.