Chang-Qin Wu

Origin of the high open circuit voltage in planar heterojunction perovskite solar cells: Role of the reduced bimolecular recombination

The high open circuit voltage is an attractive feature for the currently popular organic-inorganic hybrid perovskite solar cells. In this paper, by employing the macroscopic device model simulation, we investigate its origin for the planar heterojunction perovskite solar cells. Based on the calculated current density-voltage characteristics, it is revealed that compared to the excitonic solar cells, the fast thermal-activated exciton dissociation in the bulk due to the small exciton binding energy may improve the short circuit current and the fill factor, but its beneficial role on the open circuit voltage is marginal. The most significant contribution for the open circuit voltage comes from the reduced bimolecular recombination. In the perovskites, with the recombination prefactor many orders of magnitude smaller than that based on the Langevins theory, the internal charge density level is significantly enhanced and the density gradient is removed, leading to the high quasi-Fermi level splitting and thu...

Dynamical study on polaron formation in a metal/polymer/metal structure

By considering a metal/polymer/metal structure within a tight-binding one-dimensional model, we have investigated the polaron formation in the presence of an electric field. When a sufficient voltage bias is applied to one of the metal electrodes, an electron is injected into the polymer chain, and then a self-trapped polaron is formed at a few hundreds of femtoseconds while it moves slowly under a weak electric field (not larger than

The infrared active localized modes of soliton in trans-(CH)x☆

1.0\ifmmode\times\else\texttimes\fi{}{10}^{4}\mathrm{V}/\mathrm{c}\mathrm{m}).

Interchain coupling effects on dynamics of photoexcitations in conjugated polymers

At an electric field between

Monte Carlo simulation based on dynamic disorder model in organic semiconductors: from coherent to incoherent transport.

1.0\ifmmode\times\else\texttimes\fi{}{10}^{4}\mathrm{V}/\mathrm{c}\mathrm{m}

Effects of e-e interactions on the dynamics of polarons in conjugated polymers

and

Reversal of thermal rectification in quantum systems

8.0\ifmmode\times\else\texttimes\fi{}{10}^{4}\mathrm{V}/\mathrm{c}\mathrm{m},

Magnetic field modulated exciton generation in organic semiconductors: An intermolecular quantum correlated effect

the polaron is still formed, since the injected electron is bounded between the interface barriers for quite a long time. It is shown that the electric field applied at the polymer chain reduces effectively the potential barrier in the metal/polymer interface.

Magnetic field effects on the electroluminescence of organic light emitting devices: A tool to indicate the carrier mobility

Abstract Five localized vibrational modes have been found for the soliton in a finite ring of trans -(CH) x from the SSH model, among them three are infrared active, i.e. Goldstone, third and staggered mode, and they can be used to interpret the three observed infrared absorption lines at 900, 1260 and 1370 cm -1 .

High-resolution inelastic X-ray scattering studies of the state-resolved differential cross-section of Compton excitations in helium atoms

Within an extended Su-Schrieffer-Heeger model including interchain interactions and the extended Hubbard model, the dynamical relaxation of photoexcitations in two coupled conjugated polymer chains is investigated by using a nonadiabatic evolution method. Initially, one of the two chains is photoexcited and the other chain is in the dimerized ground state. Due to the interchain interactions, the electron and/or the hole can be transferred from one chain to the other chain. For weak interchain coupling, the dynamical evolution of the lattice on the photoexcited chain is similar to that found in an isolate single chain case. With interchain interactions increasing, the amplitude of the distortions on the photoexcited chain decreases, and simultaneously, that on the other chain gradually increases. Until stronger interchain coupling, the deformations of the two chains have almost the same amplitude. Besides intrachain polaron-excitons and intrachain oppositely charged polaron pairs as found in single chain case, interchain polaron-excitons and interchain separated charged polaron pairs are obtained. The results show that the yield of interchain products increases and that of intrachain products decreases with interchain coupling increasing. Totally, the yield of charged polarons (including intrachain oppositely charged polaron pairs and interchain oppositely charged polaron pairs) is about 25%, in good agreement with results from experiments.