Fabrication of GaN-Based Flexible VLEDs with Double-Side Light Emitting

Flexible optoelectronic devices are promising in a broad range of applications, such as virtual reality (VR), deformable displays, wearable optoelectronic devices, and consumer electronics, due to their excellent mechanical flexibility. Inorganic gallium nitride-based (GaN) semiconductor light-emitting devices with higher stability, superior color rendition, and longer lifespan have great potential for further advancing the development of flexible optoelectronic devices. In this study, we present a novel method for fabricating flexible GaN-based vertical LEDs (VLEDs). Based on the soft transparent substrate prepared by cured photosensitive resin and the single-substrate transfer technique, double-sided light output and flexible GaN-based blue VLEDs were successfully fabricated. The S-shaped electrodes in the device channel can enhance the electrode flexibility. When subjected to downward bending, the electroluminescence (EL) peak of flexible VLED shifted from 458.3 to 458.5 nm, accompanied by a decrease in EL intensity by approximately 52%. Under upward bending, the EL peak position initially exhibited a blue shift to 458.1 nm, and the luminous intensity increased by about 13% compared with the flatness state. However, the EL peak shows a red shift to 459.1 nm and a decrease of luminous intensity with further increasing the upward bending degree. These observations can be attributed to the piezo-phototronic effect. The applied external stresses can induce polarization charges at the interface of InGaN/GaN multiple quantum wells (MQWs), which alter the energy band structure of InGaN/GaN MQWs and modulate the optoelectronic properties of the device. The flexible GaN-based blue VLED with double-sided light output can provide new strategies for the development of dual-sided flexible displays and wearable human-machine interaction.