Variation of flatband potential of oxide nanocrystalline particles with core-shell structured semiconductor-MgO composites

J Bandara,U.W Pradeep

doi:10.4038/sljp.v7i0.205

Abstract

SnO 2 thin films and particles show feeble solar cell performance and poor photocatalytic activity respectively. It has been reported that coating of a thin MgO layer on SnO 2 particles results in enhancement of both solar cell performance and catalytic activities. The promoting effect of MgO layer was owing to barrier effect where MgO acts as a barrier layer for charge recombination. We noticed negative shift of flatband (FB) potential of SnO 2 with the increase of pH values and coating of a thin MgO layer on SnO 2 particles. It is shown how the negative shift in FB potential may contribute to enhance the solar cell efficiencies and photocatalytic activity in addition to the barrier effect of MgO layer.

Highlights

The primary process of any photochemical reaction is the absorption of light by a suitable light absorbing material i.e. a semiconductor or dye
In dye sensitized solar cells (DSSC), dye molecules which are attached to thin oxide film transfer excited electrons from the dye molecules to the conduction band (CB) of the oxide
It has been shown that an oxide like TiO2 follows Nernest equation and flatband potential depends on pH with the slope of -59 mV/pH and the dependence of flatband on pH was elucidated considering the following dissolution equilibrium at the TiO2 surface [19], A thermodynamic reasoning leads to the following formula for the shift in the equilibrium potential (∆θ ) of the TiO

Summary

INTRODUCTION

The primary process of any photochemical reaction is the absorption of light by a suitable light absorbing material i.e. a semiconductor or dye. In dye sensitized solar cells (DSSC), dye molecules which are attached to thin oxide film transfer excited electrons from the dye molecules to the conduction band (CB) of the oxide. Wider charge separation has been achieved using composite semiconducting materials with different band positions such as TiO2/SnO2 [10], TiO2/ZnO [11]. It has been reported about the use of an insulating layer on thin semiconducting films to increase the solar cell efficiencies and photocatalytic activities [12,13,14,15,16].

EXPERIMENTAL

RESULTS AND DISCUSSION

CONCLUSION