Polymer/cathode interface barrier limiting the open circuit voltage in polymer:fullerene organic bulk heterojunction solar cells: A quantitative analysis

Abstract

By exploring the origin of the saturation current (J0), we show that the polymer/cathode interface determines the open circuit voltage (Voc) in polymer:fullerene bulk heterojunction solar cells. We fabricate and characterize P3HT:PCBM solar cells and compare their electrical characteristics using as reference P3HT/cathode Schottky diodes. We demonstrate with thermionic emission theory that J0 has the same origin in both devices. Thus, a general barrier-dependent expression for Voc, valid for non-ohmic cathode contacts is proposed and discussed

Effects of FeCl3 as oxidizing agent on the conduction mechanisms in polypyrrole (PPy)/pc–ZnO hybrid heterojunctions grown by oxidative chemical vapor deposition

“…For that purpose, we calculated the energy barrier formed in this heterojunction according to the thermionic emission model, as given by where J 0 is the current density, and A* the Richardson constant assumed as 120 A/cm 2 T. This value is commonly found in organic semiconductors . Considering the sample's active area of around 0.09 cm 2 defined by the polymer layer, the estimated heterojunction barrier height described by (4) results in values amounting to about 0.9–1.0 eV, as listed in Table .…”

“…This value is commonly found in organic semiconductors. 12,41,42 Considering the sample's active area of around 0.09 cm 2 defined by the polymer layer, the estimated heterojunction barrier height described by (4) results in values amounting to about 0.9-1.0 eV, as listed in Table 4.…”

Spontaneous generation of interlayers in OPVs with silver cathodes: enhancing Voc and lifetime

“…A shift of the silver cathode's work function due to the interlayer will be translated to an increase in the device's V oc . 37,38 A series of direct structure OPVs composed of P3HT:PCBM blends with different HEG-DT concentrations, capped by a silver cathode, were prepared and measured. Based on previous studies on a similar system, 39 the devices were deliberately not further thermally annealed in order to demonstrate the spontaneous segregation of the additive towards the silver electrode during its deposition.…”

Effects of different formulation PEDOT:PSS hole transport layers on photovoltaic performance of organic solar cells

“…The potential barrier height was determined using the relation of lnJ versus V characteristics in the dark at room temperature …”