F4-TCNQ concentration dependence of the current—voltage characteristics in the Au/P3HT:PCBM:F4-TCNQ/n-Si (MPS) Schottky barrier diode

Abstract

In this study, we investigate some main electrical parameters of the gold/poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester:2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane/n-type silicon (Au/P3HT:PCBM:F4-TCNQ/n-Si) metal—polymer—semiconductor (MPS) Schottky barrier diode (SBD) in terms of the effects of F4-TCNQ concentration (0%, 1%, and 2%). F4-TCNQ-doped P3HT:PCBM is fabricated to figure out the p-type doping effect on the device performance. The main electrical parameters, such as ideality factor (n), barrier height (ΦB0), series resistance (Rs), shunt resistance (Rsh), and density of interface states (Nss) are determined from the forward and reverse bias current—voltage (I–V) characteristics in the dark and at room temperature. The values of n, Rs, ΦB0, and Nss are significantly reduced by using the 1% F4-TCNQ doping in P3HT:PCBM:F4-TCNQ organic blend layer, additionally, the carrier mobility and current are increased by the soft (1%) doping. The most ideal values of electrical parameters are obtained for 1% F4-TCNQ used diode. On the other hand, the carrier mobility and current for the hard doping (2%) become far away from the ideal diode values due to the unbalanced generation of holes/electrons and doping-induced disproportion when compared with 1% F4-TCNQ doping. These results show that the electrical properties of MPS SBDs strongly depend on the F4-TCNQ doping and doping concentration of interfacial P3HT:PCBM:F4-TCNQ organic layer. Moreover, the soft F4-TCNQ doping concentration (1%) in P3HT:PCBM:F4-TCNQ organic layer significantly improves the electrical characteristics of the Au/P3HT:PCBM:F4-TCNQ/n-Si (MPS) SBDs which enables the fabricating of high-quality electronic and optoelectronic devices.