Hybrid inorganic-organic light-emitting heterostructure devices based on ZnO

•Hybrid n-ZnO/p-polymer have been analyzed during the last decade for the first time.•From the ZnO point of view, four main categories are investigated.•The optoelectronic features of hybrid I/O LEDs are affected by ZnO nanostructures.•The comparison, challenges and outlooks of these hybrid LEDs have been explored. Future lighting technologies and the optoelectronic industry are dependent on novel electroluminescent devices. The hybrid inorganic/organic light-emitting diodes (I/O LEDs) have become popular to obtain high-quality displays and cost-efficient flexible smartphones with high optical features. Due to the importance of such LEDs and their place in the future, this review paper studies various hybrid I/O electroluminescent structures based on zinc oxide (ZnO) and conjugated polymers in the last decade (2010–2020) for the first time. From the ZnO point of view and its unique role in hybrid I/O LEDs, four main categories have been investigated, and the structural, electrical, and optical characteristics of each group have been carefully scrutinized and compared. These classifications include ZnO application in the near-UV range emission, ZnO for white light emission, ZnO as an electron injector/transporter layer in color emission, and ZnO electrode layer in hybrid emissive devices. Moreover, the I/O heterojunctions' basics, the electrical transport mechanism models and exciton emissions of the hybrid I/O LEDs based on ZnO have been analyzed. According to the survey, the optoelectronic features of hybrid I/O LEDs are influenced by n-type ZnO nanostructures (nanorods, nanotubes, nanowires, and nanoparticles). The electroluminescent intensity of these hybrid LEDs can be enhanced by selecting a suitable p-type conjugated polymer or by adding various dopants. Finally, the comparison, challenges, and future outlooks of these hybrid LEDs have been explored. Further hybrid LEDs based on ZnO can be designed and fabricated using nanotubes, quantum dots, and perovskite layers.