arXiv subjects

Yuanping Yi

Publications and source records attributed to Yuanping Yi.

3 recordsLinked to original sources

arXiv2022

Universal and Efficient p-Doping of Organic Semiconductors by Electrophilic Attack of Cations

Doping is of great importance to tailor the electrical properties of semiconductors. However, the present doping methodologies for organic semiconductors (OSCs) are either inefficient or can only apply to a small number of OSCs, seriously limiting their general application. Herein, we reveal a novel p-doping mechanism by investigating the interactions between the dopant trityl cation and poly(3-hexylthiophene) (P3HT). It is found that electrophilic attack of the trityl cations on thiophenes results in the formation of alkylated ions that induce electron transfer from neighboring P3HT chains, resulting in p-doping. This unique p-doping mechanism can be employed to dope various OSCs including those with high ionization energy (IE=5.8 eV). Moreover, this doping mechanism endows trityl cation with strong doping ability, leading to polaron yielding efficiency of 100 % and doping efficiency of over 80 % in P3HT. The discovery and elucidation of this novel doping mechanism not only points out that strong electrophiles are a class of efficient p-dopants for OSCs, but also provides new opportunities towards highly efficient doping of OSCs.

cond-mat.mtrl-sci↗

arXiv2014

Optical conductivity and optical effective mass in a high-mobility organic semiconductor: Implications for the nature of charge transport

We present a multiscale modeling of the infrared optical properties of the rubrene crystal. The results are in very good agreement with the experimental data that point to nonmonotonic features in the optical conductivity spectrum and small optical effective masses. We find that, in the static-disorder approximation, the nonlocal electron-phonon interactions stemming from low-frequency lattice vibrations can decrease the optical effective masses and lead to lighter quasiparticles. On the other hand, the charge-transport and infrared optical properties of the rubrene crystal at room temperature are demonstrated to be governed by localized carriers driven by inherent thermal disorders. Our findings underline that the presence of apparently light carriers in high-mobility organic semiconductors does not necessarily imply band-like transport.

cond-mat.mtrl-sci↗

arXiv2012

Symmetry Effects on Nonlocal Electron-Phonon Coupling in Organic Semiconductors

The electronic and electrical properties of crystalline organic semiconductors, such as the dispersions of the electronic bands and the dependence of charge-carrier mobility on temperature, are greatly impacted by the nonlocal electron-phonon interactions associated with intermolecular lattice vibrations. Here, we present a theoretical description that underlines that these properties vary differently as a function of the symmetry of the nonlocal electron-phonon coupling mechanism. The electron-phonon coupling patterns in real space are seen to have a direct and significant impact on the interactions in reciprocal space. Our findings demonstrate the importance of aspects that are usually missing in current transport models. Importantly, an adequate description of the electronic and charge-transport properties of organic semiconductors requires that the models take into account both antisymmetric and symmetric contributions to the nonlocal electron-phonon coupling mechanism.

cond-mat.mtrl-sci↗