Synergetic effects of a front ITO nanocylinder array and a back square Al array to enhance light absorption for organic solar cells

Abstract

Efficient light management is critical to obtain high performance for organic solar cells (OSCs), which aims to solve the contradiction between limited carrier extraction and light absorption for the normally employed photoactive layers generally having both short exciton diffusion lengths and low extinction coefficients. In this study, we introduce a simple and efficient light management structure consisting of a front indium tin oxide nanocylinder (ITO-NC) array and a back square Al array. Thanks to the synergetic effects of antireflection and light scattering induced by the ITO-NC array, together with the secondary scattering and localized surface plasmon resonance because of the square Al array, remarkably enhanced light absorption in a broad spectral range can be achieved. Taking the most investigated photoactive layer of the P 3 H T : P C 61 B M blend as an example, simulation results reveal that, compared with the planar control device of the I T O / P E D O T : P S S / P 3 H T : P C 61 B M ( 80 n m ) / Z n O / A l , the short-circuit current density and power conversion efficiency can be enhanced by 36.58% and 38.38% after incorporating the light management structure with the optimal structural parameters. Furthermore, good omnidirectional light management can be achieved for the proposed device structure. Given the excellent performance and simple structure, we believe that this study would provide a meaningful exploration of developing light management structures applicable for thin film-based optoelectronic devices.