High performance organic ultraviolet photodetectors based on novel phosphorescent Cu(I) complexes

• Highly efficient organic UV-PDs using two Cu(I) complexes as acceptors were obtained.
• The optimized UV-PD offers a high photoresponse of 560 mA/W.
• The reasons for such high response are analyzed in detail.
• The working mechanism of harvesting high performance is also discussed.

We demonstrate highly efficient organic ultraviolet photodetectors using 4,4′,4′′-tris[3-methyl-pheny(phenyl)amino]triphenylamine (m-MTDATA) and two excellent phosphorescent Cu(I) complexes, [Cu(DPEphos)(DPPz)]BF4 (CuDD) (DPEphos = Bis[2-(diphenylphosphino)phenyl]ether, DPPz = dipyrido(3,2-a:2′,3′-c) phenazine) and [Cu(DPEbenz)(DPPz)]BF4 (CuBD) (DPEbenz = 1,2-bis(diphenylphosphino)benzene) to act as the electron donors and acceptors, respectively. The optimized photodetector based on CuDD delivers a photocurrent of 588 μA/cm2 at −12 V, corresponding to a response of 560 mA/W under an illumination of 365 nm UV light irradiation with an intensity of 1.05 mW/cm2 and a detectivity of 2.82 × 1011 cm Hz1/2/W. The high response is attributed to the larger band offset at m-MTDATA/CuDD heterojunction, the suppression of radiative decay of m-MTDATA and efficient electron transfer from m-MTDATA to CuDD. The working mechanism of harvesting high performance is also discussed in detail.