Abstract
We have studied the doping concentration dependence of the thermoelectric (TE) properties for the n- and p-doped CaIn
2
P
2
layered Zintl phase at two fixed temperatures: T = 600 and 900 K through first-principles electronic band structure calculations combined with Boltzmann's transport theory within charge-carrier relaxation time and rigid band approximations. The band structure calculated using the Tran-Blaha modified Becke-Johnson potential shows a fundamental indirect energy band gap (E
g
) of 1.10 eV that comes from the polyanion (In
2
P
2
)
−2
. CaIn
2
P
2
exhibit a mixture of flat and dispersive energy bands in the energy window from
to
eV, which is a required characteristic for high electrical transport coefficients. The computed lattice thermal conductivity for CaIn
2
P
2
is equal to
at 900 K and
at 1250 K. This relatively low lattice thermal conductivity of CaIn
2
P
2
can be mainly attributed to its layered crystalline structure. The highest value of the figure of merit of CaIn
2
P
2
, viz. ZT = 0.73 (0.71), is obtained for an optimal electron (hole) concentration of
(
) at 900 K.