The record laboratory cell (1 cm2 area) efficiency for thin - film cadmium telluride
(CdTe) is 16.5%, and that for a copper indium diselenide (CuInSe2) thin - film alloy
is 19.5%. Commercially produced CdTe and CuInSe2 modules (0.5–1 m2 area) have
efficiencies in the 7–11% range. Research is needed both to increase laboratory cell
efficiencies and to bring those small - area efficiencies to large - area production. Increases
in laboratory CdTe cell efficiency will require increasing open - circuit voltage, which
will allow cells to harvest more energy from each absorbed photon. This will require
extending the minority carrier lifetime from its present τ  2 ns to τ  10 ns and in -
creasing hole concentration in the CdTe beyond 1015 cm2, which appears to be limited by
compensating defects. Increasing laboratory CuInSe2 - based cell efficiency significantly
beyond 19.5% will also require increasing the open - circuit voltage, either by increasing
the bandgap, the doping level, or the minority carrier lifetime. The photovoltaic cells in
commercial modules occupy tens of square centimeters, and both models and exper -
iments have shown that low - performing regions in small fractions of a cell can signif i -
cantly reduce the overall cell per form ance. Increases in commercial module efficiency
will require control of ma te rials properties across large deposition areas in a high -
throughput environment to minimize such non - uniformities. This ar ticle discusses ap -
proaches used and research needed to increase the ultimate efficiencies of CdTe - and
CuInSe2 - based devices and translate these gains to commercial photovoltaic modules.