Fabrication And Characterization Of Organic Ultraviolet Photodetectors Based On PBD And Balq Electron Acceptors

Ultraviolet photodetectors (PDs) have been attracting a great deal of interest owing to its broad applications in industrial, environmental, astronomical, medical, biological arenas. Organic films that hold ultra-low price, simple fabrication, and large-scale production render us with a alternative to fabricate UV PDs. Until now, the majority of previously reported organic UV PDs reveal photoresponse in the near UV region, with peak response at roughly365nm, and exhibit photoresponse in visible region. Even though a few reports showed a300-350nm response, the photocurrent response and dark current density were in poor-quality. In the deep UV region, reported devices employed thin Al cathode as a window for the incident light, which with front-illuminated models is detrimental to fabricate plane arrays.According to the above analysis, we employed ITO/glass substrates in organic near UV devices and PEDOT:PSS/quartz substrates in organic deep UV devices. NPB donor, TAPC donor, PBD acceptor, and BAlq acceptor were used, respectively. Main results are list below.1.We use TAPC donor and PBD acceptor for fabricating near UV PDs. TAPC:PBD heterojunctions (HJs) can operate at316-346nm, revealing a peak response of0.12A/W at~330nm. And we also extend its response to the deep UV region via the structure of quartz/Al/PEDOT:PSS (PH1000)/PEDOT:PSS (4083)/TAPC:PBD/LiF/Al;2.The deep UV PDs with the architecture of quartz/Al/PEDOT:PSS (PH1000)/PEDOT:PSS (4083)/NPB/PBD/LiF/Al were fabricated. The PDs extend response to the deep UV region, exhibit response ranging from200to400nm. A photo-to-dark current ratio of more than103, a peak photocurrent response of0.18A/W under280nm light illumination with an intensity of0.488mW/cm2;3. Bulk PDs with the structure of quartz/PEDOT:PSS (PH1000)/NPB:BAlq/LiF/Al were successfully fabricated. The PDs reveal a response peak at~270nm;4. We fabricated different structures by employing TAPC donor and BAlq acceptor, containing TAPC:BAlq bulk HJs and TAPC/TAPC:BAlq/BAlq mixed HJs. Bulk HJs of quartz/Al/PEDOT:PSS (PH1000)/PEDOT:PSS (4083)/TAPC:BAlq/LiF/Al exhibit a peak photocurrent response of100.8mA/W at~280nm, and mixed HJs of quartz/Al/PEDOT:PSS (PH1000)PEDOT:PSS (4083)/TAPC/TAPC:BAlq/BAlq/LiF/Al show a peak photocurrent response of33.6mA/W at～260nm.