High-Performance Infrared Light-Emitting Diodes Based on Chirality-Sorted Carbon Nanotube Films

An important goal in the carbon nanotube (CNT) optoelectronics is to achieve a high-performance near-infrared (NIR) light source. But there are still many challenges such as CNT chirality purity, defects, thin film quality and device structure design. Here, we realized high-performance infrared light-emitting diodes (LEDs) based on the high chirality purity (10, 5) single-walled carbon nanotubes (SWCNTs) network film. Asymmetric palladium (Pd) and hafnium (Hf) contacts were used as the holes and electrons injection electrodes of the LEDs, respectively. However, the large Schottky barrier between the Hf electrode and CNTs, resulting from the polymer wrapped on the CNT surface during the sorting process, leads to difficult electron injection and low efficiency of electroluminescence (EL). We found that the electron injection efficiency could be improved by the local doping of the CNT channel with dielectric layers of YOX-HfO2, which reduced the Schottky barrier for electron injection from Hf electrodes. At last, our CNT LED device exhibits a high external quantum efficiency (EQE) of about 5×10-4 without any optical coupling structure. It shows an EL peak at the optical communication O band of 1290 nm with a simple structure and low work voltage. It’s believed that the chiral CNT infrared light source has great application potential in the field of the CNT monolithic optoelectronic integrated system and on-chip optical interconnection.