Thin Film Cadmium Zinc Telluride Solar Cells

A process for fabricating thin film heterojunction solar cells with cadmium zinc telluride (Cd
_1-x
Zn
_x
Te) absorbers is described. Cd
_1-x
Zn
_x
Te films with composition from 0lesxles0.6 were deposited by a simple vapor transport (VT) process at 550degC onto moving CdS-coated substrates. Post-deposition thermal treatment in halide vapor ambient yielded high photocurrent, limited primarily by window layer optics. Similar cell performance is demonstrated for ZnCl
₂
and CdCl
₂
vapors using treatment protocols which retain film composition. Solar cell efficiency >12% has been achieved for cells with 0 < x < 0.10 (1.50 eV < E
_g
< 1.58 eV) and efficiency > 8.5% has been achieved for cells with 0.1 < x < 0.3 (1.58 < E
_g
< 1.60eV). No enhancement of V
_oc
with increasing band gap has been found and may be related to window-absorber interfacial reactivity and resulting junction non-uniformity