Energy transfer ultraviolet photodetector with 8-hydroxyquinoline derivative-metal complexes as acceptors

We choose 8-hydroxyquinoline derivative-metal complexes (Beq, Mgq, and Znq) as the acceptors (A) and 4,4′,4"-tri-(2-methylphenyl phenylamino) triphenylaine (m-MTDATA) as the donor (D) respectively to study the existing energy transfer process in the organic ultraviolet (UV) photodetector (PD), which has an important influence on the sensitivity of PDs. The energy transfer process from D to A without exciplex formation is discussed, differing from the working mechanism of previous PDs with Gaq [Zisheng Su, Wenlian Li, Bei Chu, Tianle Li, Jianzhuo Zhu, Guang Zhang, Fei Yan, Xiao Li, Yiren Chen and Chun-Sing Lee 2008 Appl. Phys. Lett. 93 103309)] and REq [J. B. Wang, W. L. Li, B. Chu, L. L. Chen, G. Zhang, Z. S. Su, Y. R. Chen, D. F. Yang, J. Z. Zhu, S. H. Wu, F. Yan, H. H. Liu, C. S. Lee 2010 Org. Electron. 11 1301] used as an A material. Under 365-nm UV irradiation with an intensity of 1.2mW/cm², the m-MTDATA:Beq blend device with a weight ratio of 1:1 shows a response of 192mA/W with a detectivity of 6.5 × 10¹¹ Jones, which exceeds those of PDs based on Mgq (146mA/W) and Znq (182mA/W) due to better energy level alignment between m-MTDATA/Beq and lower radiative decay. More photophysics processes of the PDs involved are discussed in detail.