Organic Deep Ultraviolet Photodetector With Response Peak Focusing on 270 nm Using the Acceptor BAlq

An organic deep ultraviolet (DUV) photodetector (PD) with a response peak at 270 nm was fabricated. NPB and BAlq were employed as electron donor and acceptor, respectively, and polymer PEDOT:PSS was used as the transparent anode. The peak response of 0.14 A/W under illumination of 270-nm light with an intensity of 1.35 mW/cm
²
and a detectivity of 8.26×10
¹¹
cmHz
^1/2
W
^-1
at -12 V were achieved, and the corresponding quantum efficiency η reaches 64.3%. The PDs exhibit a low dark current of 8.97×10
^-8
A/cm
²
, and the photo-to-dark current ratio is about 2.1×10
³
at -12 V. The realization of DUV detection is attributed to the strong absorption of shorter UV wavelengths of acceptor BAlq and high transmittance of PEDOT:PSS anode in DUV region. The mechanism of harvesting high performance is also discussed in detail.