Light-emitting, energy-harvesting, and sensing technologies could all benefit from optoelectronic materials that can convert light energy into electricity and electricity into light. However, devices leveraging these materials are notoriously inefficient, wasting a considerable amount of valuable energy in the form of heat. New light-electricity conversion principles can break the present efficiency restrictions. Inversion symmetry is a physical property that restricts engineers’ control over electrons in the material and their ability to develop unique or efficient devices. It is a limitation for many materials with efficient optoelectronic features.
For the first time, a team of materials scientists and engineers employed a strain gradient to break the inversion symmetry of molybdenum disulfide (MoS2), resulting in a novel optoelectronic phenomenon.
The scientists placed a vanadium oxide (VO2) wire underneath a sheet of molybdenum disulfide. Because MoS2 is a flexible material, it deformed its original shape to follow the curve of the VO2 wire, creating a gradient within its crystal lattice. The gradient breaks the material’s inversion symmetry, allowing the manipulation of electrons traveling within the crystal.