Computer Simulation of The Effect of Band Cap Grading of The Cigs Absorber Layer on The Performance of Cds/Cigs Thin Film Solar Cell

Luqman Sufer Ali,Anas Khalid Abdullah

doi:10.33899/rengj.2012.50478

Abstract

In this paper, the effect of the band gap grading of the absorber layer Copper Indium Gallium Selenide (CIGS), which is a compound semiconductor, on the performance of the solar cell has been studied. CIGS has a tuneable band gap and it varied with the composition of the semiconductor. This study has been accomplished using the computer simulation program SCAPS-1D. The program was developed to study the photonic devices especially CIGS and CdTe thin film solar cells. The effect of the grading shape (Front, Back and Double Grading) on the performance of the cell has been studied so as to improve the efficiency of the cell. Keywords: Band Gap Grading, CIGS, SCAPS-1D.

Highlights

Copper Indium Gallium Selenide Cu(In,Ga)Se2 (CIGS) is an interesting material for solar cell applications
The output parameters of the base line cell with a uniform band gap equal to 1.15 eV are Voc=638.8 mV, Jsc=34.307 mA/cm2, FF%=79.59 % and η=17.44%. 3.1 Front Grading At open circuit conditions the dominant part of the recombination is expected to occur in the space charge region (SCR)
When the band gap increased within the SCR the recombination processes can be reduced due to the increasing in the barrier height resulting in improved Voc as shown in Fig.(6)

Summary

1.Introduction

Copper Indium Gallium Selenide Cu(In,Ga)Se2 (CIGS) is an interesting material for solar cell applications. (1) Structure of the CIGS solar (~20%) for thin film devices in testing As the solar cell industry continues to expand there is great opportunity for CIGS based devices to become a significant technology in direct solar to electric conversion [2]. The band gap of CIS is around 1.04 eV, whereas by adding Ga into the ternary system of CIS, the band gap energy of the CIGS quaternary system can be varied over a range of 1.04 to 1.68 eV. This property can be used to engineer the band gap of the CIGS when it used as absorber layer in the solar cell and to make a cell with a graded band gap [3]. Where ΔEg is the change in band gap over the distance x due to the Ga-grading

Device Simulation

Front Grading Simulation

Back Grading Simulation

Results and Discussion

4.Conclusions