Decent efficiency improvement of organic photovoltaic cell with low acidic hole transport material by controlling doping concentration

Abstract

Presently, poly (3, 4-ethylenedi-oxythiophene): polystyrene sulfonic acid (PEDOT:PSS) is most commonly used hole transport material (HTM) in photovoltaic (PV) cells but its higher acidity, hygroscopicity, high price have motivated people to develop a good substitute. Here, we prepare a series of PSS doped polyaniline (PANI) with synergic (around 90%) transmittance and work function value (within 5.09-5.16 eV) varying PSS concentrations to check the possible utility as HTM in a poly (3-hexylthiophene): [6,6]-indene-C60 bisadduct based organic photovoltaic (OPV) cell. Here, it is observed that, because of change in conductivity, the PV performance of those OPV devices is strongly dependent on the doping concentration of the HTM and, at optimized PSS concentration, PANI:PSS has higher conductivity. This facilitates better hole extraction efficiency into the PV device and results in higher short circuit current density (J(SC)). Therefore, the PANI:PSS-based OPV device with optimized PSS concentration exhibits same level of power conversion efficiency (PCE: 4.5 +/- 0.2%) as a PEDOT:PSS based OPV device. Thus, a lower acidic (pH = 2.2) p-type semiconductor PANI:PSS (weight ratio = 1:1 and) can be a good alternative to highly acidic (pH = 1.7) PEDOT:PSS (weight ratio = 1:6, Clevious Al 4083) for using as HTM in an OPV device.