Effects of defect states on the performance of CuInGaSe₂solar cells

Abstract

Device modeling has been carried out to investigate the effects of defect states on the performance of ideal CuInGaSe 2 (CIGS) thin film solar cells theoretically. The varieties of defect states (location in the band gap and densities) in absorption layer CIGS and in buffer layer CdS were examined. The performance parameters: open-circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency for different defect states were quantitatively analyzed. We found that defect states always harm the performance of CIGS solar cells, but when defect state density is less than 10 14 cm 3 in CIGS or less than 10 18 cm 3 in CdS, defect states have little effect on the performances. When defect states are located in the middle of the band gap, they are more harmful. The effects of temperature and thickness are also considered. We found that CIGS solar cells have optimal performance at about 170 K and 2 m of CIGS is enough for solar light absorption.

Toward High‐Efficiency CIGS‐based Thin‐film Solar Cells Incorporating Surface Defects Layer, through a Comparative Study of Electrical Characteristics—SCAPS 1D Modeling

“…The most efficient cell is the one where the SDL is modeled (CIGS/SDL/ZnS/ZnO). This is in good agreement with the work of Wan et al in 2014 [ 22 ] and Ouédraogo et al in 2014, [ 12 ] who showed that the modeling of the SDL would make it possible to get closer to the real model of a cell structure. It is also in line with Touafek et al [ 13 ] statement who advocated that the formation of a SDL play a major role in the suppression of interface recombination, enabling improving the performance.…”

A comprehensive photovoltaic study on tungsten disulfide (WS2) buffer layer based CdTe solar cell

“…However, when the defect density increases more than 10 17 cm −3 , V OC increases from 0.85 V and reaches 1.05 V for the defect density of 10 19 cm −3 . The alteration in V OC for the defect density of 10 19 cm −3 , can be attributed to the built-in electric field of the p–n junction which has the opposite direction compared with the normal p–n junction [ 10 , 39 ]. The current density J SC shows a steady level until the defect density goes beyond 10 17 cm −3 and then, it sharply reduces to 2.91 mA/cm 2 from 28.40 mA/cm 2 .…”

“…As buffer layer thickness increases, the amounts of photons absorbed outside the hole diffusion length region increase which may lower the recombination rate [ 37 ]. There is not much effect of TCO SnO 2 layer thickness, thus it has been kept at a minimum value to achieve low series resistance [ 38 , 39 ]. The optimized thicknesses can be found in Table 1 .…”