Ongoing evolutions in nanoscience resonate exceptionally well with the societal need for smaller, faster, and more efficient consumer devices. Semiconducting quantum dots (QDs) occupy a central role in this revolution as their unique size-tunable and atomic-like energy states are in high demand for luminescent color conversion and lasing. Over the last decade, bottom-up approaches have emerged as scalable methods to assemble complex nanostructured QDs with exceptional control over their size and shape. Current research efforts are directed toward synthesizing high-quality indium phosphide (InP) QDs as InP combines a tunable bandgap throughout the visible range with high oscillator strength transitions. To make QDs suitable for devices, QDs are typically produced as core/shell heteronanostructures. Building on pre-existing knowledge of epitaxially grown quantum well structures and previous generations of quantum dots, I foresee that significant breakthroughs can be realized by methodically engineering the interface in core/shell heteronanostructured QDs. To do so, I will design innovative core/shell heteronanostructured QDs with structurally and electronically decoupled interfaces. On the one hand, these will serve as a model system to discover general principles of interfacial control at the nanoscale. Simultaneously, my approach will result in InP-based QDs with strongly improved linear and non-linear optical properties, as desired for luminescent down-conversion and lasing.