Graphene-Based semiconductor heterostructures for optoelectronic devices

Awide variety of optoelectronic devices based on graphene has been and are still being studied, and some of them have already reached a level of competitiveness comparable to conventional semiconductor devices. However, single-layer graphene has low light absorbance (only 2.3%) in the ultraviolet to near infrared region, short light-matter interaction length, and high sheet resistance, unfavourable for light harvesting applications. In addition, the ultra-short lifetime of excitons in pure graphene resulting from its gapless nature also leads to fast carrier recombination, which limits the efficient production of photocurrent or photovoltage. However, graphene transparent conductive electrodes are highly attractive for optoelectronic device applications due to their extremely-high carrier mobilities, almost-perfect transmittance, and high flexibility, and the sheet resistance can be lowered by a simple doping technique. The emergence of graphene/ semiconductor hybrid heterostructures provides a platform useful for fabricating high-performance optoelectronic devices such as photodetectors, solar cells, and light-emitting diodes, thereby overcoming the inherent limitations of graphene. Here, I report our recent studies of optoelectronic devices based on graphene/semiconductor hybrid heterostructures, composed of graphene, graphene quantum dots, Si quantum dots/nanowires, perovskites, organic materials, and GaN, with being assisted by doping of graphene.