Role of the CdS buffer layer as an active optical element in Cu(In,Ga)Se₂thin‐film solar cells

Abstract

ZnO/CdS/Cu(In,Ga)Se2 (CIGS) thin‐film heterojunction solar cells with CdS buffer layers of thicknesses between 0 and 85 nm are characterized by current–voltage, quantum efficiency, and optical reflection measurements. We investigate the correlation between the short‐circuit current density and the CdS layer thickness, focusing on the counteracting effects of light absorption and reduced optical reflection induced by the CdS layer. Both effects almost compensate each other for CdS layer thicknesses between 0 and 40 nm. Thus, an optimization of the short‐circuit current density is not achieved by omitting the CdS layer, but rather by replacing the CdS buffer with an alternative buffer material with higher bandgap energy and optical constants similar to those of CdS. Copyright © 2002 John Wiley & Sons, Ltd.

Improvement of photon collection in Cu(In,Ga)Se2 solar cells and modules by fluorescent frequency conversion

“…In addition, light with a wavelength λ ≤ 515 nm is partly absorbed in the 50-70 nm thick CdS buffer layer with a band gap energy E g = 2.4 eV. Only a percentage of the photogenerated electron hole pairs from the CdS contribute to the short circuit current density J SC [1,2] whereas photons absorbed in the ZnO window layer with E g = 3.2 eV are totally lost. These optical losses are a sizeable part of the standard AM1.5G solar spectrum [3].…”

Efficient Double Buffer Layer Sb2 (SexS1–x)3 Thin Film Solar Cell Via Single Source Evaporation

“…However, there are several challenges for CdS based antimony chalcogenide solar cells. Utilizing thicker ETL film would sacrifice short light absorption, while too thin CdS thickness may lead to short‐circuiting between rough FTO and absorber layer . To consider the benefits of CdS ETL and reduce the CdS thickness, it can be modified with an additional pre‐layer as used in CdTe solar cells .…”

In Situ thickness measurements of chemical bath-deposited CdS

“…This time will occur at different CdS-thicknesses depending on the substrate, but at this time the light that would be absorbed by the completed device will be maximized. This maximization has been shown to correlate to more efficient devices [22].…”