A high fill-factor complementary vertical thermoelectric device is described. In some embodiments, a plurality of lower electrodes is disposed upon a supporting structure. Pairs of thermoelectric elements of complementary conductivity type are disposed on the lower electrodes, such that each lower electrode couples together a respective complementary pair of adjacent thermoelectric elements disposed thereon. A conformal dielectric layer is formed over the thermoelectric elements of one conductivity type, the thickness of the conformal layer on the sidewalls of these elements determining the spacing between adjacent pairs of complementary thermoelectric elements. A plurality of upper electrodes, each straddling a pair of adjacent lower electrodes and coupling together a complementary pair of adjacent thermoelectric elements may complete the high fill-factor complementary thermoelectric device.