Performance of ITO-free inverted organic bulk heterojunction photodetectors: Comparison with standard device architecture Articles uri icon

publication date

  • October 2013

start page

  • 2484

end page

  • 2490

issue

  • 10

volume

  • 14

international standard serial number (ISSN)

  • 1566-1199

electronic international standard serial number (EISSN)

  • 1878-5530

abstract

  • We report on the fabrication of Indium Tin Oxide (ITO)-free inverted organic bulk heterojunction (BHJ) photodetectors of poly(3-hexylthiophene) (P3HT): 1-(3-methoxycarbonyl)propyl-1-1-phenyl-(6,6) C61 (PCBM). The final inverted device structure is Cr/Al/Cr/P3HT:PCBM/poly-3,4-ethylenedioxythiophene:poly-styrenesulfonate (PEDOT:PSS)/Ag (Zimmermann et al., 2009) [1]. The device is top-absorbing with the light entering through the hole contact grid. We have fabricated standard devices with structure ITO/PEDOT:PSS/P3HT:PCBM/LiF/Al in order to carry out a comparison study. Inverted photodetectors show slightly higher quantum efficiency and responsivity compared to standard devices. Frequency responses at different bias voltages were measured showing a maximum -3 dB cut-off frequency of 780 kHz and 700 kHz at -3 V for the standard and inverted structures respectively. Parameters extracted from the fit of a circuital model to the impedance spectroscopy measurements were used to estimate the photodiode cut-off frequency as function of bias.

keywords

  • ito-free; organic photodetector; inverted structure; p3ht:pcbm