A hybrid ZnO/BaTiO3 nano-network for the enhancement of the energy harvesting

Energy-level matching and stress transfer are significant characters of heterojunction to achieve excellent carrier generation and transportation behavior for energy harvesting. Here, we proposed a novel flexible nanogenerator built by ITO/PET layers spin-coated with ZnO/BaTiO3 heterojunction composite, whose electrical output performance can be largely enhanced due to the nano-network constructed by BaTiO3 microspheres and ZnO nanorods. Under periodic stress, varying temperature field and contact-separation conditions, the energy harvesting capacity of ZnO/BaTiO3 nanogenerator is enhanced greatly compared with pure BaTiO3 one, which can be attributed to the improvements of stress and carrier transport efficiency depending on the network structure and energy band matching in ZnO/BaTiO3 heterojunction. The maximum output voltage and current are improved by 6.6 and 4.38 times to 7.2 V and 0.07 μA, respectively, after the polarization treatment by applied electric field, due to the ferroelectric domain rearrangement. While the highest output current reach to 1.0 μA and 2.0 μA for contact-separation and varying temperature modes as TENG and PyENG, respectively. A DFT theoretical result is obtained that electrons accepting/losing capacities of ZnO/BaTiO3 heterojunction are improved with increasing pressure according to the plane-averaged electron density difference. These results indicate that this simply-made multimode nanogenerator can be a promising candidate for energy harvesting under different external excitations.