(386e) Colloidal Synthesis of Zinc Tin Phosphide Nanocrystals

Our growing energy usage has created an urgent need for sustainable sources of electricity and optoelectronic devices including photovoltaics and lighting. Successful development of such technologies relies on the discovery of scalable photonic materials that can compete with current state-of-the-art III-V (GaN, GaAs) semiconductors but have low toxicity and processing costs. Composed of abundant, non-toxic, and recyclable elements, we present the II-IV-V₂ system ZnSnP₂ as a candidate for such applications. Ternary pnictides such as ZnSnP₂ offer the potential of tuning the band gap via cation disorder at fixed compositions. Realizing the potential of ZnSnP₂, however, has been difficult to accomplish. Syntheses have typically led to impure materials due to the difficulty of controlling the presence of defect phases and anti-site defects, leading to uncontrollable optoelectronic properties. In this work, we present a hot-injection colloidal synthesis method as a defect-limited route to ZnSnP₂. We obtain nanocrystals approximately 4 nm in size; we determine crystal phase via x-ray diffraction measurements, pair distribution function analysis, and transmission electron microscopy imaging and further study the local structure of our nanocrystals via x-ray absorption spectroscopy. Optical spectroscopy measurements taken over the growth period of the nanocrystals provide insight on the evolution of structure-property relationships in the synthesized nanocrystals.