Quantum dot light-emitting diodes with high external quantum efficiency and luminous power efficiency are realized through in situ thermal annealing of a quasi-monolayer of colloidal nanocrystals on a crosslinked hole-transport layer. Partial desorption of quantum-dot surface ligands and improved film morphology contribute to better electrical injection from the organic layers to the quantum dots, resulting in a 3 to 4 fold enhancement of device efficiency with emission exclusively from the quantum dots.