Table 1.

TCOs employed in photovoltaic cells (after Fortunato [5]).

Cell Type	TCO	Dopants
$\left.\begin{array}{c}a-\mathrm{Si}:{\text{H}}^{\S }\\ \mu \text{c}-\mathrm{Si}:{\text{H}}^{\S }\\ \mathrm{HIT}-\mathrm{Si}:{\text{H}}^{\S }\end{array}\right\}$	$\begin{array}{c}\mathrm{Sn}{\text{O}}_2\\ \text{I}{\text{n}}_2{\text{O}}_3\\ \mathrm{ZnO}\end{array}$	$\begin{array}{c}\text{F},\mathrm{Sb}\\ \mathrm{Sn}\\ \mathrm{Al},\mathrm{In},\mathrm{Ga}\end{array}$
Cu(In,Ga)Se${}_2$	In${}_2$O${}_3$	Sn
	ZnO	Al, In, Ga
CdTe	SnO${}_2$	F, Sb
	Cd${}_2$SnO${}_4$	-
Dye-sensitized Graetzel	TiO${}_2$*	-
	SnO${}_2$	F, Sb
	In${}_2$O${}_3$	Sn
OPV	high work-function${}^{‡}$	-

${}^{\S }$ a-Si: amorphous silicon, μc: microcrystalline, HIT: heterojunction with intrinsic layer

* anatase TiO${}_2$

${}^{‡}$ higher work function required than currently available [5]