Bipolarons in poly(3-methylthiophene): Spectroscopic, magnetic, and electrochemical measurements

Optical measurement of doping efficiency in poly(3-hexylthiophene) solutions and thin films

“…The same 1.6 eV peak was previously reported and correlated with electron spin resonance studies (ESR) of doped P3HT solutions. 19 This peak was attributed to bipolarons and believed to be the equilibrium charge-storage configuration in doped P3HT solutions. Furthermore the spin per charge approached zero when the doping level was higher than 1%, supporting the bipolaron hypothesis.…”

“…19 The decomposition of F4TCNQ-doped P3HT solution absorption (A doped ) into five components can be summarized with the following expression:…”

“…Colaneri et al, for instance, combined optical absorption with magnetic and electrochemical measurements to determine the type of charge species in electrochemically doped poly(3-methylthiophene) thin films. 19 Ziemelis et al also used optical measurements to determine injected carrier types in metal-insulatorsemiconductor structures with poly(3-hexylthienylene). 20 In this work, however, we are interested in characterizing charged species in molecularly-doped semiconducting polymer thin films.…”

Measurement of Small Molecular Dopant F4TCNQ and C60F36 Diffusion in Organic Bilayer Architectures

“…The diffusion of dopant molecules within and between layers of a device can greatly hinder the performance by causing unwanted interactions with other materials, but there have been very few studies directly investigating this process. 11,18,19 The first doping experiments were performed using atomic dopants such as iodine and bromine 20,21 and later using atoms such as lithium, cesium, and strontium. 22,23 However, those dopants are all too small.…”

Triplet Paramagnetic Centers in Conducting Polymers – Study by ESR and SQUID

“…The magnetic properties of polythiophene depend on the nature of substituents in the ring. The susceptibility of undoped polythiophene is low and increases upon doping (Chen et al, 1986), whereas the susceptibility of undoped alkyl -substituted polythiophenes is high and decreases upon doping (Colaneri et al, 1987;Čík et al, 2005), and the χT-T plots are nonlinear in many cases. (iii) There is no correlation between the degree of crystallinity and the value of χ P. The existence of the Pauli susceptibility is considered to serve as a strong argument in favor of the metallic regions.…”