Fabrication of Cu(In_x,Ga_1-x)Se₂ Superstrate Thin Film Solar Cell using Binary Phases

Abstract

Currently, substrate thin film solar cells with Cu(In,Ga)Se2(CIS) absorbers yield conversion efficiencies of up 20.4%, the highest published efficiency of CIS superstrate thin film solar cells is 12.8%. It is the maximum efficiency when composition is as follow; Cu, In and Se was 1, 1 and 2.

The maximum efficiency of CIS superstrate thin film solar cell is smaller than that of CIS substrate thin film solar cell, but manufacturing cost of CIS superstrate is lower than that of CIS substrate since the reduce of the manufacturing process. In addition, CIS absorber layer is fabricated through binary phases to reduce the process temperature and processing price.

In this study, CIS superstrate thin film solar cell was fabricated to reduce the device manufacturing cost and CIS absorber layer was deposited by the binary phases. By using substrate (Sodalime Glass,SLG), window layer(i-ZnO, Al:ZnO)were deposited on n-type transparent electrode layer in the upper part. CIS absorber was respectively deposited by In₂Se₃ and CuSe in a binary phases by using MBE(Molecular Beam Epitaxy). The deposited sample went through heat process, and then electrode was created to fabricate the device. In order to identify the structural and electrical characteristics depending on CuSe deposition time, CIS absorber and CIS solar cell device, analysis was conducted by using XRD (X-ray Diffractometer, Bulk, PANalytical), FE-SEM (Field Emission Scanning Electron Microscope, S-4800, HITACHI), ICP(Inductively Coupled Plasma, ICPS-8100, Shimadzu),SIMS (Secondary Ion Mass Spectrometry, IMS 6F, CAMECA) and solar-simulator(AM1.5g, 100 mW/cm₂).

Keywords:

• Cu(In
• Ga)Se₂
• superstrate
• thin film solar cell
• binary
• co-evaporation