Solution-processed PbTe nanocrystal (NC) thin films are ligand exchanged by ethylenediamine and then annealed at 400 °C for enhancement of NC coupling. To further improve the performance, heterostructures are introduced into the PbTe/PbS films. Significantly, an optimized ZT of ≈0.30 is successfully achieved at 405 K. This method opens an avenue toward thermoelectric thin film devices with high performance.