Open AccessHigh sensitivity and fast response solution processed polymer photodetectors with polyethylenimine ethoxylated (PEIE) modified ITO electrode
Author(s) -
Yue Wang,
Lihua Zhu,
Yufeng Hu,
Zhenbo Deng,
Zhidong Lou,
Yanbing Hou,
Tao Feng
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.007719
Subject(s) - materials science , photodetector , optoelectronics , dark current , electrode , polymer solar cell , photocurrent , energy conversion efficiency , chemistry
Most organic photodetectors utilize a bulk heterojunction (BHJ) photo-active film due to its high exciton dissociation efficiency. However, the low dark current density, a key role in determining the overall performance of photodetectors, is hardly achieved in the BHJ structure since both the donor and acceptor domains are in contact with the same electrode. The most popular strategy to overcome this problem is by fabricating bilayer or multilayer devices. However, the complicated fabrication process is a challenge for printing electronics. In this work, we demonstrate a solution processed polymer photodetector based on a poly (3-hexylthiophene) (P3HT): (phenyl-C61-butyric-acid-methyl-ester) (PC 61 BM) blend film with polyethylenimine ethoxylated (PEIE) modified ITO electrode. The transparent PEIE efficiently blocks the unnecessary electronic charge injection between the active film and the electrode, which dramatically decrease the dark current. Under illumination, the photoexcited charges accumulated in the PEIE modified ITO region finally can tunnel through the barrier with the help of the applied reverse bias, leading to a large photocurrent. Therefore, the resulting polymer photodetector shows a 2.48 × 10 4 signal-to-noise ratio (SNR) under -0.3 V bias and an 11.4 MHz bandwidth across the visible spectra under a small reverse bias of 0.5 V. The maximum EQE of 3250% in the visible wavelength is obtained for the polymer photodetector at -1 V under 370 nm (3.07 μW/cm 2 ) illumination. This solution processed polymer photodetector manufacturing is highly compatible with the flexible, low-cost, and large area organic electronic technologies.