Carbon Photodetectors: The Versatility of Carbon Allotropes

Carbon‐based organic electronics are a technology, with the potential of complementing and substituting opto‐electronic devices based on inorganic semiconductors and metals. In the group of organic semiconductors, carbon allotropes come with outstanding opto‐electric properties and are remarkable candidates for novel applications like printed electronics via solution‐processing on mechanically flexible, robust and light weight substrates, while reducing the environmental impact. Carbon allotropes like fullerenes, graphene quantum dots (GQD), carbon nanotubes (CNT), graphene and also diamond are especially interesting for photodetectors due to their tunable bandgap, high absorption coefficients and high charge carrier mobilites. These unique opto‐electric properties of the allotropes, which strongly depend on their molecular dimensionality (0D, 1D, 2D and 3D), allow each allotrope to be used in a preferential range. Hence, relying on the intrinsic properties of carbon allotropes or by hybridization, carbon‐based photodetectors are built for a spectral bandwidth, reaching from gamma‐rays to THz radiation. This review highlights the recent advances in photodetectors based on fullerenes, GQDs, CNTs, graphene and diamond, with the focus on room temperature‐operated devices. The versatility of multi‐dimensional carbon allotropes is outstanding, and promising results outline the maturing of all carbon‐based photodetection across the technologically relevant wavelengths. Carbon based photodetectors for γ‐ray to THz detection are reviewed. With focus on carbon allotropes (C60, GQD, CNTs, graphene and diamond) their unique opto‐electric properties are highlighted in conjunction with recent advance in various room‐temperature operated photo‐detectors. Performances, which challenge inorganic detectors, are presented and demonstrate the promising future and versatility of carbon allotropes for photodetection across the electromagnetic spectrum.