Universal photocurrent-voltage characteristics of dye sensitized nanocrystalline TiO$_2$ photoelectrochemical cells

TL;DR

This paper introduces a universal, linearizable model for the nonlinear photocurrent-voltage behavior of dye-sensitized TiO$_2$ solar cells, enabling prediction of complete curves and fill factors from minimal data.

Contribution

It presents a new first-principles-based model that unifies diverse experimental data into a single universal function for TiO$_2$ dye-sensitized solar cells.

Findings

Experimental data collapse onto a universal function after renormalization.

Complete current-voltage curves and fill factors can be estimated from three data points.

The model provides physical insights into high fill factors and their dependence on open circuit voltage.

Abstract

We propose a new linearizable model for the nonlinear photocurrent-voltage characteristics of nanocrystalline TiO$_2$ dye sensitized solar cells based on first principles and report predicted values for fill factors. Upon renormalization diverse experimental photocurrent-voltage data collapse onto a single universal function. These advances allow the estimation of the complete current-voltage curve and the fill factor from any three experimental data points, e.g., the open circuit voltage, the short circuit current and one intermediate measurement. The theoretical underpinning provides insight into the physical mechanisms responsible for the remarkably large fill factors as well as their known dependence on the open circuit voltage.