Revisiting the interpretation of biased luminescence: Effects on Cu(In,Ga)Se2 photovoltaic heterostructures

Abstract

We analyzed the luminescence signal under electrical bias (Lum-V) for several Cu(In,Ga)Se2 solar cells having different absorber growth processes and different buffer layers such as CdS and ZnS. A numerical model is developed taking into account optical and electrical properties of the complete heterostructures. It appears that the absorber-buffer interface has a crucial role in explaining the different behaviors. Our interpretation is based on the quasi Fermi level splitting (QFL) linked to both the applied voltage and the luminescence intensity. Lum-V experiments and its dependence on illumination intensity are discussed and could be used to access transport properties when looking at the depth variation of the QFL and offer a classification of the possible cases.

Quantitative luminescence mapping of Cu(In, Ga)Se2 thin‐film solar cells

“…Previous theoretical studies predicted such depths variations of the qFl splitting . It is also worth noting that they were recently experimentally evidenced, using luminescence both spatially and spectrally integrated, under various illuminations and voltages .…”

The Optical Diode Ideality Factor Enables Fast Screening of Semiconductors for Solar Cells

“…PL has been used in the past to study and predict the role of different recombination channels in the finished devices for various solar technologies. But these studies had a different purpose than our study.…”

“…But these studies had a different purpose than our study. In several investigations the measurements were performed on finished solar cells or the goal was to determine the recombination activity of grain boundaries or the radiative recombination coefficient . In another study an approach similar to ours was used to differentiate between bulk and interface recombination.…”

Optoelectronic Properties of Layered Perovskite Solar Cells

“…The origin of the small slope in the bias‐dependent PL experiment is still not understood. In the literature, an exponential‐like variation has already been observed for CIGS or CdTe (cadmium telluride) solar cells and was explained by solving the drift‐diffusion equation and calculating the local quasi Fermi level splitting in the absorber region . Developing an advanced model for the bias‐dependent luminescence of high‐performance perovskite solar cells could deliver a deep inside into the effect of interlayers, contact selectivity, and defects in these devices.…”