Design and Fabrication of PERC-Like CdTe Solar Cells Using Micropatterned Al2O3 Layer

Recent studies have investigated novel strategies to further improve the limited
$V_{oc}$
of CdTe solar cells via increased carrier lifetime and doping density of CdTe thin films. Among various metal oxides, aluminum oxide (Al
2
O
3
) is a promising passivation candidate, where the negatively charged Al
2
O
3
layer repels the minority carrier in CdTe and Al
2
O
3
provides a chemically passivating interface, increasing the carrier lifetime. Despite the continuing efforts, an optimized back-contact architecture to improve the
$V_{oc}$
while maintaining high
$J_{sc}$
and
$FF$
is still under development. In this work, we report the design, fabrication, and characterization of PERC-like CdTe solar cells, where an Al
2
O
3
passivation layer is patterned using laser-beam lithography. Our process enables reproducible patterning on a rough surface CdTe while maintaining the size of the array in the design. Analysis of CdTe PERC devices (As-doped) shows a notably different
$V_{oc}$
trend compared to
$FF$
and
$J_{sc}$
, independent of the patterned array structures used in this study. The subsurface electronic structure of CdTe and the interplay between carrier selectivity and collection of the patterned Al
2
O
3
could be responsible for the observed PV characteristics.