Long afterglow SrAl2O4:Eu,Dy phosphors for CdS quantum dot-sensitized solar cells with enhanced photovoltaic performance

Abstract

An efficient bifunctional structured layer composed of long afterglow SrAl₂O₄:Eu,Dy phosphors on top of a transparent layer of nanocrystalline TiO₂ was fabricated for use in CdS quantum dot-sensitized solar cells (QDSSCs). The introduction of SrAl₂O₄:Eu,Dy increases the photocurrent of the QDSSCs mainly due to enhanced light harvesting abilities via improved light absorption and scattering. Under one sun illumination (AM 1.5G, 100 mW cm⁻²), cells containing SrAl₂O₄:Eu,Dy show a marked improvement in their conversion efficiency (1.24%) compared with cells without SrAl₂O₄:Eu,Dy (0.98%). After one sun illumination for 1 min, after which the light source was turned off, cells containing SrAl₂O₄:Eu,Dy show an efficiency of 0.07% under dark conditions due to the irradiation by the long persistent light from SrAl₂O₄:Eu,Dy. The present strategy should provide a possibility to fulfil the operation of solar cells even in the dark.