Quantitative theory of the grain boundary impact on the open-circuit voltage of polycrystalline solar cells

Published

December 12, 2018

Author(s)

Benoit H. Gaury, Paul M. Haney

Abstract

The techniques used to grow polycrystalline thin films are known to produce a wide variety of structural defects. However, recent developments in thin-film photovoltaics have led to high photovoltaic conversion efficiencies despite large densities of grain boundaries. Here we theoretically study how the inhomogeneities in the properties of grains and grain boundary networks impact the open-circuit voltage V oc of polycrystalline solar cells. We provide an analytical, quantitative expression for the grain boundary dark current that accounts for the size, grain boundary orientation, gap states configuration and recombination strength. We show that for high hole mobilities and sufficiently large grains, grain boundaries are decoupled and contribute independently to the total recombination current. In addition, we find that near Voc , grain boundary recombination currents depend only algebraically (not exponentially) on electrical or structural parameters, limiting the impact of grain boundary inhomogeneities on Voc . Our model bridges the gap between the grain boundary properties observed with nanoscale characterization and the macroscale device open-circuit voltage.

Citation

ACS Applied Energy Materials

Volume

2

Issue

1

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acsaem.8b01246

Citation

Gaury, B. and Haney, P. (2018), Quantitative theory of the grain boundary impact on the open-circuit voltage of polycrystalline solar cells, ACS Applied Energy Materials, [online], https://doi.org/10.1021/acsaem.8b01246 (Accessed May 21, 2024)