ABSTRACT: InP-based quantum dots (QDs) have become the most highlighted candidates to be a less-toxic surrogate for Cd- and Pb-based optoelectronic devices. However, the development of InP QDs still lags due to the expensive and flammable phosphorus precursors. Herein, we introduce sodium phosphaethynolate as an alternative, cheap and low-toxic phosphorus source for the synthesis of highly emitting InP-based QDs. The resulting QDs possess a size-tunable photoluminescence wavelength range between 465 and 620 nm and high emission quantum yield between 43 and 97%. The proof-ofconcept QD light-emitting diodes applying the InP-based QDs as an emitter layer exhibit a maximum external quantum efficiency of 1.47%, 6.88%, and 13.62% for blue, green, and red devices, respectively. These results prove the applicability and processability of this new phosphorus in the preparation of high-quality InP-based QDs.