Space charge region effects in bidirectional illuminated P3HT:PCBM bulk heterojunction photodetectors

作者：Buechele Patric; Morana Mauro; Bagnis Diego; Tedde Sandro Francesco; Hartmann David; Fischer Rene; Schmidt Oliver

来源：Organic Electronics, 2015, 22: 29-34.

DOI：10.1016/j.orgel.2015.03.027

• Organic semiconductor
• Oxygen doping
• Spray-coating
• Band bending
• Pinning
• Space charge region

Organic semiconductors are widely investigated for their application in photovoltaics and photodetectors. We show that the efficiency of these devices is strongly influenced by the position of the space charge region, due to unintentional doping, and wavelength-dependent absorption properties in bulk heterojunctions. Spray-coated P3HT:PCBM bulk heterojunction photodiodes with thicknesses up to 4.2 mu m and semitransparent top contact enable the characterization of exciton generation and separation in both irradiation directions. A large difference in external quantum efficiency (EQE) is observed for top and bottom illuminated configurations and is explained by a bias dependent arrangement of the space charge region at the two contact electrodes. Numerical drift-diffusion simulations allow to get insight into first order mechanisms behind the spectral features of EQE data in highly-doped organic photodiodes.

• 出版日期2015-7