Fabrication of carbon nanotube-threephase organic photodetectors with high responsivity and wide spectrum and the underlying mechanisms

Abstract

In this work, we incorporated single-walled carbon nanotubes (SWCNTs) into organic three-phase heterojunction active layer detectors, and systematically experimentally investigated the influences of single walled carbon nanotubes (SWCNTs) on the photoabsorption and photoelectric properties of the organic three-phase heterojunction detectors. Under -1 V bias voltage, the average photoresponsivity of three primary colors detector is 475 mA/W, about 2–3 times higher than that of similar devices that without SWCNTs. The average external quantum efficiency (EQE) increases to 111%. The results show that the incorporation of single-walled carbon nanotubes in the three-phase bulk heterojunction active layer maintains the original spectral morphology, while increases a higher degree of aggregation and crystallinity of the organic conjugated polymer, and further enhances a larger capacity of light absorption, regardless of the number of active layer's mixed phases. Under -1 V bias voltage, the average photoresponsivity of three primary colors detector is 475 mA/W, about 2–3 times higher than that of similar devices. The average external quantum efficiency (EQE) can be increased to 111%. In terms of carrier transport, SWCNT can increase the exciton dissociation area, dissociation rate of the film, and provide a fast transport channel for the charge, therefore improve the charge collection of the electrode. In a concentration range of 0.75–1.75 wt% and in high-energy photon excitation, single-walled carbon nanotubes can produce a multiple exciton generation.