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Colloidal quantum dots, with their size-tunable optoelectronic properties and scalable synthesis, enable applications in which inexpensive high-performance semiconductors are needed. Synthesis science breakthroughs have been key to the realization of quantum dot technologies, but important group III–group V semiconductors, including colloidal gallium arsenide (GaAs), still cannot be synthesized with existing approaches. The high-temperature molten salt colloidal synthesis introduced in this work enables the preparation of previously intractable colloidal materials. We directly nucleated and grew colloidal quantum dots in molten inorganic salts by harnessing molten salt redox chemistry and using surfactant additives for nanocrystal shape control. Synthesis temperatures above 425°C are critical for realizing photoluminescent GaAs quantum dots, which emphasizes the importance of high temperatures enabled by molten salt solvents. We generalize the methodology and demonstrate nearly a dozen III-V solid-solution nanocrystal compositions that have not been previously reported. 

Quantum dot color converters (QDCCs) are a leading technology for enhancing the gamut and efficiency of displays, notably in QD‐OLED TVs and monitors. However, cadmium‐free QDs require thick layers for effective color conversion. Our novel inorganic photoresist densely packs InP QDs, achieving over 60% PLQY and optical density of 1 at less than 10 µm thickness, advancing QDCCs for high‐performance microLED displays. Patterning of 5 µm pixels with high fidelity is also demonstrated.