INVESTIGATION OF BUFFER LAYERS, FRONT AND BACK CONTACTS FOR ZnxCd1- xS/CdTe PHOTOVOLTAIC

Abstract

A numerical analysis was executed utilizing Analysis of
Microelectronic and Photonic Structures (AMPS 1D)
simulator to explore the possibility of higher efficiency
and stable ZnxCd1-xS/CdTe cells among several cell
structures with indium tin oxide (ITO) and cadmium
stannate (Cd2SnO4) as front contact, zinc stannate
(Zn2SnO4) and zinc oxide (ZnO) insertion as buffer
layer and antimony telluride (Sb2Te3) insertion with
Nickle (Ni) as back contact was conducted in the
conventional (SnO2/CdS/CdTe/Ag) CdTe cell structures
in which CdS is replaced by zinc cadmium sulphide
(ZnxCd1-xS) as window layer. Efficiency as high as
18.0% has been found with 80 nm of ZnxCd1-xS window
layer for x=0.05, 1 µm of CdTe layer and 100 nm
Zn2SnO4 buffer layer without Sb2Te3 back contact.
However, ZnO insertion shows low conversion
efficiency of 7.84% and 12.26%, respectively with and
without Sb2Te3 back contact. Moreover, it was found
that the cell normalized efficiency linearly decreases
with the increasing operating temperature at the
temperature gradient of -0.25%/°C.