Highly Sensitive Hybrid Oxide Phototransistors with Photoresponsive Zeolitic-Imidazolate-Frameworks for Real-Time Light Detection

Conventional oxide-based thin-film phototransistors (Ph-TRs) with a hybrid structure with additional photoabsorbers show limitations in real-time on/off operations without additional input bias. Here, hybrid InGaZnO (IGZO) Ph-TRs utilizing zeolitic-imidazolate-framework-67 (ZIF-67), an electrically insulating material with a unique metal-to-metal charge transfer (MMCT) pathway enabling charge migration, are presented. A wide photodetection range and fast response/recovery speed without additional gate bias are achieved. In particular, ZIF-67 used as a photoabsorber exhibits absorption of visible light over a wide range of wavelengths. Photoexcited electrons migrate through the MMCT pathway between Co ions and migrate to the IGZO conduction band, causing a significant change in the photocurrent (I-ph) of the hybrid ZIF-67/IGZO Ph-TR. In the dark, ZIF-67 immediately returns to the insulating state, resulting in a fast rise/fall time under dynamic photo-stimulus. In addition, it exhibits repeatable photo-sensing performance without persistent photocurrent behavior under pulsed light-on/off cycles. A high photosensitivity of 10(8) for red light (592 nm, 0.1 mW cm(-2)) is obtained as it suppresses the dark current and amplifies photocurrent generation in the subthreshold gate voltage region. This combination of fast response time, high photosensitivity, and high stability is promising for ideal Ph-TRs, enabling real-time detection even for high-frequency operations.

Automated summary

Hybrid InGaZnO (IGZO) phototransistors (Ph-TRs) with zeolitic-imidazolate-framework-67 (ZIF-67) as a photoabsorber demonstrate wide photodetection range, fast response/recovery speed, and high stability without additional gate bias. ZIF-67 absorbs visible light and transfers photoexcited electrons to the IGZO conduction band through a metal-to-metal charge transfer pathway, resulting in significant changes in photocurrent. The fast rise/fall time and repeatable photo-sensing performance under pulsed light-on/off cycles make it promising for real-time detection even at high frequencies.