Enhanced Performance of Flexible Hybrid Solar Cells via Silver Nanoparticle Incorporation

Flexible hybrid heterojunction solar cells (HHSCs) utilizing a heterojunction of thin, flexible silicon (Si) with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are quite promising owing to their lightweight, cost-effectiveness, simple device design, low-temperature fabrication, and notable performances. However, effective light harvesting for thin Si without surface nano/microstructuring and poor charge transport properties of the polymer are pressing issues for efficient flexible HHSCs. Here, plasmonic silver nanoparticles (Ag NPs) of ∼30 nm diameter are introduced into the PEDOT:PSS matrix to overcome such challenges. The Ag NPs are synthesized by a cost-effective, simple chemical reduction approach (Turkevich method). The role of Ag NPs on the fabrication and performance of ≤50 μm thin, flexible Si-based HHSCs has been investigated as a function of Ag NP concentration. The incorporation of 0.75 wt % in PEDOT:PSS led to ∼21% enhancement in the power conversion efficiency without any additional surface structuring of Si. Enhanced light trapping, electrical conductivity of the polymer layer, and charge carrier transport, facilitated by the Ag NPs in the polymer matrix, are attributes of the device performance. The mechanism of improved light trapping is explained via the fascinating plasmonic properties of Ag NPs. The electrical conductivity of the Ag NPs and PEDOT:PSS matrix is explained by improved charge transfer in the polymer. Such a concept, which can avoid conventional surface micro/nanostructuring steps for flexible Si-based solar cells, has not been explored yet and holds immense potential to enhance performance.