Analytical and numerical modeling of capacitance voltage characteristics of organic solar cells

TL;DR

This paper develops an analytical and numerical model to describe the capacitance-voltage characteristics of organic solar cells, explaining unusual peaks and validating results with simulations, while discussing limitations of traditional analysis methods.

Contribution

It introduces a charge-based analytical model for organic solar cell C-V characteristics and validates it with numerical simulations, addressing limitations of existing methods.

Findings

The model explains the peak in C-V characteristics observed experimentally.

Validation of the model with self-consistent numerical simulations.

Discussion on the limitations of Mott-Schottky analysis for organic devices.

Abstract

We report a charge based model to establish the analytical equation, describing the nature of capacitance-voltage ($C$-$V$) characteristics of organic solar cells under dark condition (or organic diodes) over a wide range of voltage, extending from deep reverse bias to well above the built-in potential. The present model enables to explain the unusual peak in $C$-$V$ characteristics of these devices, as observed experimentally by various groups. The results are further validated using self-consistent numerical simulation. Finally, we discuss the discrepancy and limitation of using Mott-Schottky relation to extract the built-in potential, doping density etc. in organic solar cells/diodes.