Plasmonic Enhancement of Biosolar Cells Employing Light Harvesting Complex II Incorporated with Core–Shell Metal@TiO2 Nanoparticles

Abstract

Here the study of effects of plasmonic nanoparticles (PNPs) conjugated with natural extract light‐harvesting complex II (LHCII) is reported. Three types of core–shell metal@TiO2 PNPs with distinct surface plasmonic resonance are prepared. The plasmonic adsorption of the metal core provides strong photon capture and enhances the LHCII excitation through plasmon‐induced resonance energy transfer (PIRET). More efficient charge separation is facilitated at LHCII/TiO2 interface as revealed by quenching of the fluorescence and reduction of the fluorescence lifetime of LHCII after adsorbing on PNPs. Femtosecond transient absorption provides further conclusive proof for charge injection from excited LHCII into the TiO2 conduction band. The plasmonic effects are further demonstrated in the enhanced photovoltaic properties after incorporating the PNPs in LHCII‐sensitized solar cells built on a 3D TiO2 nanotree photoanode. The photocurrent is enhanced by all PNPs under illumination of the full solar spectrum and the selected wavelength windows around Soret and Q bands of LHCII trimer, and the “dark region” between them. This study reveals that the core–shell PNPs can enhance the LHCII‐sensitized solar cells based on multiple mechanisms, including enhancing light harvesting, promoting PIRET from PNP to LHCII, and facilitating charge injection from excited LHCII into TiO2.