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

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.