SHORT COMMUNICATION: ACCELERATED PUBLICATION: Diode characteristics in state-of-the-art ZnO/CdS/Cu(In1?xGax)Se2 solar cells

Abstract

We report a new state of the art in thin‐film polycrystalline Cu(In,Ga)Se2‐based solar cells with the attainment of energy conversion efficiencies of 19·5%. An analysis of the performance of Cu(In,Ga)Se2 solar cells in terms of some absorber properties and other derived diode parameters is presented. The analysis reveals that the highest‐performance cells can be associated with absorber bandgap values of ∼1·14 eV, resulting in devices with the lowest values of diode saturation current density (∼3×10−8 mA/cm2) and diode quality factors in the range 1·30 < A < 1·35. The data presented also support arguments of a reduced space charge region recombination as the reason for the improvement in the performance of such devices. In addition, a discussion is presented regarding the dependence of performance on energy bandgap, with an emphasis on wide‐bandgap Cu(In,Ga)Se2 materials and views toward improving efficiency to > 1;20% in thin‐film polycrystalline Cu(In,Ga)Se2 solar cells. Published in 2005 John Wiley & Sons, Ltd.

Chemical incorporation of copper into indium selenide thin‐films for processing of CuInSe2 solar cells

“…The highest efficiency cells reported to date (19.5%) were made from copper-poor Cu(In, Ga)Se 2 (CIGS) deposited by the threestage process [1]. In this vacuum co-evaporation process an (In, Ga) 2 Se 3 layer is deposited and then converted into a Cu-rich CIGS layer by exposure to Cu and Se fluxes at high temperature before further evaporation of In, Ga and Se turn the layer Cu-poor [2].…”

Surface potential of chalcopyrite films measured by KPFM

“…With their high power conversion efficiencies on the laboratory scale, thin film solar cells from the Cu-chalcopyrite materials system are a promising candidate for this technology; in fact, pilot production lines have recently been started. Currently, the highest efficiency of nearly 20% is obtained for Cu(In, Ga)Se 2 containing ≈ 30% of Ga [1]. A typical solar cell consists of a metallic Mo layer on a float glass substrate, a polycrystalline p-type Cu-chalcopyrite absorber layer with a typical thickness of 2 µm, a thin buffer layer (typically CdS) and the n-type double layer window (ZnO).…”

Effects of magnetic fields on free excitons in CuInSe2

“…Despite a great potential and considerable amount of research carried out on this material the achieved efficiency of CIS-based solar cells, of about 20% [1], is significantly lower than 30%, the theoretical limit for one junction solar cell. This suggests a lack of understanding of the physical properties of this material.…”