Optical model for multilayer structures with coherent, partly coherent and incoherent layers

Rudi Santbergen,Arno H.M Smets,Miro Zeman

doi:10.1364/oe.21.00a262

Abstract

We present a novel approach for modeling the reflectance, transmittance and absorption depth profile of thin-film multilayer structures such as solar cells. Our model is based on the net-radiation method adapted for coherent calculations and is highly flexible while using a simple algorithm. We demonstrate that as a result arbitrary multilayer structures with coherent, partly coherent and incoherent layers can be simulated more accurately at much lower computational cost.

Highlights

Optical models for thin-film multilayer structures are used in several important applications such as design and analysis of optical coatings and thin-film solar cells
For accurate calculation of these parameters it is crucial that the interference between multiple internal reflections is taken into account correctly. Far this has been especially challenging for thin-film solar cells which typically have an absorber layer thickness on the order of the coherence length of the incident sunlight
The fringes at shorter wavelengths due to interference in the ZnO:Al layer are independent of the degree of coherence of the absorber layer

Summary

Introduction

Optical models for thin-film multilayer structures are used in several important applications such as design and analysis of optical coatings and thin-film solar cells. For accurate calculation of these parameters it is crucial that the interference between multiple internal reflections is taken into account correctly Far this has been especially challenging for thin-film solar cells which typically have an absorber layer thickness on the order of the coherence length of the incident sunlight. The conventional approach to model these multilayer systems is to treat the coherent layers first, after which these are represented as interfaces in an incoherent calculation [4, 5]. By combining the coherent net-radiation method with a more efficient averaging procedure we obtained an elegant optical model for arbitrary multilayer systems consisting of coherent, partially coherent and incoherent layers

Coherent net-radiation method

E E ib ic

Incoherent layers

Partially coherent layers

Findings

Conclusion