Front and back contact parameters.

Parameter	Front contact			Back contact
	Initially	After optimization		Initially	After optimization
Material	Graphene	ITO	Al	Au	Ag
Thickness	1L–5L (1L = 0.334 nm)	80 nm	80 nm	10 μm	10 μm
Optical properties	n = 2.7	ITO nk (default)	n = 1.19	Au nk (default)	Ag nk (default)
	k = 1.45		k = 7.05
Work function (eV)	4.31	4.4	4.06	5.4	4.64
	4.50	4.45	4.20		4.74
	4.54	4.5	4.26
	4.77
	4.90
Absorption loss	0.023 (constant)	ITO abs (default)	0.056	0	0
External reflection	1L = 0	ITO Ref (default)	0.868	0	0
	2L = 0.023
	3L = 0.046
	4L = 0.070
	5L = 0.092
Surface condition	Plane	Plane	Plane	Plane	Plane
Internal reflection	0	0	0	0	0