• Leiviskä, Miina A. T.
• Dong, Jingjin
• Koster, Lja
• Heiber, Michael C.
• Liu, Jian
• Portale, Giuseppe, A.
• Koopmans, Marten
• Hummelen, Jan

Abstract

<p>High electrical conductivity is a prerequisite for improving the performance of organic semiconductors for various applications and can be achieved through molecular doping. However, often the conductivity is enhanced only up to a certain optimum doping concentration, beyond which it decreases significantly. We combine analytical work and Monte Carlo simulations to demonstrate that carrier-carrier interactions can cause this conductivity decrease and reduce the maximum conductivity by orders of magnitude, possibly in a broad range of materials. Using Monte Carlo simulations, we disentangle the effect of carrier-carrier interactions from carrier-dopant interactions. Coulomb potentials of ionized dopants are shown to decrease the conductivity, but barely influence the trend of conductivity versus doping concentration. We illustrate these findings using a doped fullerene derivative for which we can correctly estimate the carrier density at which the conductivity maximizes. We use grazing-incidence wide-angle X-ray scattering to show that the decrease of the conductivity cannot be explained by changes to the microstructure. We propose the reduction of carrier-carrier interactions as a strategy to unlock higher-conductivity organic semiconductors.</p>

Topics

• density
• impedance spectroscopy
• microstructure
• simulation
• semiconductor
• electrical conductivity
• wide-angle X-ray scattering