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

Abstract

We investigate photoluminescence and electroluminescence (PL and EL) emission images from Cu(In, Ga)Se 2 -based solar cells by means of a Hyperspectral Imager. Using the generalized Planck's law, maps of the effective quasi-Fermi level splitting eff in absolute values are obtained. A good agreement is found between the spatially averaged splitting in PL and the global open-circuit voltage. However, from a local carrier transport discussion, we conclude that the equality does not hold locally. The spatial variations are rather attributed to local depth variations of the quasi-Fermi level splitting due to material properties spatial fluctuations. By comparing PL and EL emissions, we discuss qualitatively the local effective lifetimes and collection efficiencies.

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

“…This must lead to an increase of the quasi Fermi levels within the absorber although the QFL value at each terminal is fixed (i.e., the external voltage V). 25 Therefore, at a given voltage, the luminescence intensity is increasing with the excitation power and, at a given excitation power, the variation of the luminescence intensity might not be purely exponential with the applied voltage.…”

Absorption Coefficient of a Semiconductor Thin Film from Photoluminescence

“…However, for a real PL measurement, the signal in the high absorption range is limited by noise, which depends on the experimental setup, sample, and measurement conditions. But a 2-to 3-order-of-magnitude difference between the PL peak maximum and the noise level is typically reported [31,[35][36][37][38][39][40]. Thus, random noise is introduced so that the high-energy side of the PL signal can be resolved over intensities spanning 3 orders of magnitude [the blue crosses in Fig.…”

Experimental evidence of hot carriers solar cell operation in multi-quantum wells heterostructures

“…Moreover, under PL excitation and without electrical bias, it is a good measure of the open circuit voltage, 2,19 falling within 10 meV of the Voc in a number of cases. [20][21][22] We have measured quantitatively the QFLs and the carrier temperature in both the QWs and the barrier energy region, using the methods developed in Refs. 18 and 23 and shortly outlined below.…”