  We present a \MF{terahertz} quantum cascade laser operating on a
thermoelectric cooler up to a record-high temperature of 210.5 K. The active
region design is based on only two quantum wells and achieves high temperature
operation thanks to a systematic optimization by means of a nonequilibrium
Green's function model. Laser spectra were measured with a room temperature
detector, making the whole setup cryogenic free. At low temperatures ($\sim 40
K), a maximum output power of 200 mW was measured.
