TY - JOUR
T1 - Photocurrent deviation from linearity in an organic photodetector due to limited hole transport layer conductivity
AU - Euvrard, J.
AU - Revaux, A.
AU - Kahn, Antoine
AU - Vuillaume, D.
N1 - Funding Information:
Work in Princeton was supported by a grant from the National Science Foundation ( DMR- 1807797 ). AK thanks the group of Prof. Seth Marder for providing the dopants.
Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2020/1
Y1 - 2020/1
N2 - It has been demonstrated that p-doped polymer layers are a convenient replacement as hole transport layer (HTL) for the widely used Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), yielding comparable photodetection performances at low light intensities. In this work, we aim to evaluate the response of organic photodetectors (OPDs) with increasing light intensity when p-doped PBDTTT-c is used as HTL. Photocurrent linearity measurements are performed on devices processed with both PEDOT:PSS and p-doped PBDTTT-c to better determine the role of the HTL. We show a deviation of the photocurrent from linearity for light intensities above 10−3 W/cm2 at 0 V applied bias due to distinct mechanisms depending on the HTL material. While space charge limited photocurrent (SCLP) explains the non-linearity at high light intensity for the device processed with PEDOT:PSS, bimolecular recombination is responsible for the loss in linearity when p-doped PBDTTT-c is used as HTL. The replacement of PEDOT:PSS by p-doped PBDTTT-c, which is 6 orders of magnitude less conductive, induces Langevin recombination, causing photocurrent non-linearity. Therefore, this study emphasizes the need for highly conductive transport layers when photodetection applications are targeted, and motivates further improvements in organic semiconductor doping.
AB - It has been demonstrated that p-doped polymer layers are a convenient replacement as hole transport layer (HTL) for the widely used Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), yielding comparable photodetection performances at low light intensities. In this work, we aim to evaluate the response of organic photodetectors (OPDs) with increasing light intensity when p-doped PBDTTT-c is used as HTL. Photocurrent linearity measurements are performed on devices processed with both PEDOT:PSS and p-doped PBDTTT-c to better determine the role of the HTL. We show a deviation of the photocurrent from linearity for light intensities above 10−3 W/cm2 at 0 V applied bias due to distinct mechanisms depending on the HTL material. While space charge limited photocurrent (SCLP) explains the non-linearity at high light intensity for the device processed with PEDOT:PSS, bimolecular recombination is responsible for the loss in linearity when p-doped PBDTTT-c is used as HTL. The replacement of PEDOT:PSS by p-doped PBDTTT-c, which is 6 orders of magnitude less conductive, induces Langevin recombination, causing photocurrent non-linearity. Therefore, this study emphasizes the need for highly conductive transport layers when photodetection applications are targeted, and motivates further improvements in organic semiconductor doping.
KW - Organic photodetectors
KW - Organic semiconductor doping
KW - Photocurrent linearity
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U2 - 10.1016/j.orgel.2019.105450
DO - 10.1016/j.orgel.2019.105450
M3 - Article
AN - SCOPUS:85072192205
SN - 1566-1199
VL - 76
JO - Organic Electronics: physics, materials, applications
JF - Organic Electronics: physics, materials, applications
M1 - 105450
ER -