Effect of PEDOT band structure on conductive polymer-insulator-silicon junctions

Abstract

The effect of replacing a conventional metal with an organic conductive polymer in a metal-insulator-semiconductor (MIS) diode is examined theoretically and experimentally. Two sets of MIS diodes, one with gold and the other with poly(3,4-ethylenedioxythiophene) as the top “metal”, have been manufactured in parallel. Despite the two conductors having similar reported work functions of 5.1 eV to 5.2 eV, the hybrid devices exhibited far lower current densities as compared to their inorganic counterparts. Simulating the device behaviour reveals the limited width of the energy bands in the conductive polymer as the reason for low current density in the hybrid MIS.

Superstructured Optoionic Heterojunctions for Promoting Ion Pumping Inspired by Photoreceptor Cells

“…Localized bands were induced between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) after doping because of the appearance of polaron and dipolaron, which was the result of the strong interaction of carriers with polymer chains and deformation of the chains . The E F of PEDOT:PSS tends to be below the localized bands with favoring the transport of holes, indicating that PEDOT:PSS can serve as a p-type organic semiconductor generally …”

“…39 The E F of PEDOT:PSS tends to be below the localized bands with favoring the transport of holes, indicating that PEDOT:PSS can serve as a p-type organic semiconductor generally. 40 The interfacial band alignment of the rGO/PEDOT:PSS heterojunction is displayed in Figure 4a. The photoexcited holes in rGO can be transferred to PEDOT:PSS, while the photoexcited electrons in PEDOT:PSS can be transferred to rGO.…”

Charge Carrier Transport, Trapping, and Recombination in PEDOT:PSS/n-Si Solar Cells

“…The difference between the work function of PEDOT:PSS and silicon (0.5 eV) is smaller than the value derived from C – V measurements (0.615 eV). Taking into account a systematic error of UPS measurements of ±0.1 eV, the observed mismatch can be explained by the presence of the Au top electrode with slightly higher work function of 4.9 eV or 5.1 eV …”

“…However, electrons have a chance to overcome a lower potential barrier in the space-charge region of Si, thus contributing to the forward current. Carrier exchange is possible in the case of alignment of the conduction band of Si with upper states of PEDOT bipolaron bands, the distances of which from the HOMO band are near 0.98 and 1.14 eV, correspondingly 36 (see Figure 8). The present mechanism is confirmed by the observation of an Arrhenius behavior of the saturation current J 01 with an activation energy, which matches well with the built-in potential φ B .…”