排序方式: 共有16条查询结果,搜索用时 15 毫秒
1.
苯环取代聚乙炔是一类具有简并基态的发光聚合物.利用扩展的SuSchriefferHeeger模型,研究了这类聚合物链中的孤子、极化子等元激发特性.结果表明:由于苯环与聚乙炔主链间的强π电子耦合,苯环取代抑制了聚乙炔主链的二聚化,减小了导带与价带之间的能隙;因此取代聚乙炔中的元激发具有较小的激发能,同时具有更大的相干长度.尽管苯基取代对元激发有很大的影响,但是非取代聚乙炔中元激发的基本物理规律依然成立,表明这些元激发的基本特性不受取代基团的影响
关键词:
孤子
极化子
苯基取代聚乙炔 相似文献
2.
3.
Being driven by an external electric field a polaron carrying both spin 1/2 and charge ±e moves at a constant speed in a polymer chain. When the polaron passes through a specific site, which couples to a magnetic impurity via spin-exchange interactions, its spin undergoes a spin-flip process if it is antiparallel to the impurity spin. Our numerical simulation shows that (a) a swap-like operation is performed between the polaron and impurity during the scattering process (b) polarons might be good candidates to be information carriers in the molecular scale. 相似文献
4.
The effect of interface hopping on inelastic scattering of oppositely charged polarons in polymers 下载免费PDF全文
The inelastic scattering of oppositely charge polarons in polymer heterojunctions is believed to be of fundamental importance for the light-emitting and transport properties of conjugated polymers. Based on the tight-binding SSH model, and by using a nonadiabatic molecular dynamic method, we investigate the effects of interface hopping on inelastic scattering of oppositely charged polarons in a polymer heterojunction. It is found that the scattering processes of the charge and lattice defect depend sensitively on the hopping integrals at the polymer/polymer interface when the interface potential barrier and applied electric field strength are constant. In particular, at an intermediate electric field, when the interface hopping integral of the polymer/polymer heterojunction material is increased beyond a critical value, two polarons can combine to become a lattice deformation in one of the two polymer chains, with the electron and the hole bound together, i.e., a self-trapped polaron-exciton. The yield of excitons then increases to a peak value. These results show that interface hopping is of fundamental importance and facilitates the formation of polaron-excitons. 相似文献
5.
6.
7.
从离散的SSH模型出发,考虑了链内的电子相互作用,以及由杂质和周围链上的荷电孤子产生的库仑势的影响,探讨了各种掺杂浓度的反式聚乙炔中孤子晶格的能谱与电子束缚态。计算结果表明:在孤子晶格的能谱中,在价带底有两条定域能级,在导带顶存在着多个电子束缚态,随掺杂浓度的升高,束缚态的局域性减弱,禁带中的孤子能级形成孤子能带。当掺杂浓度高达16.67%时,所有的电子束缚态都消失,转变为扩展态。孤子晶格的禁带宽度随着掺杂浓度的增加而增大,最高占据态与导带底之间的能隙则随之逐渐减小。孤子能带底与价带顶之间的能隙在临界浓度附近有一极大值。还讨论了电子-电子相互作用对孤子晶格能谱的影响。
关键词: 相似文献
8.
采用一维紧束缚近似的SSH模型,计算了不同强度的电场下高聚物中一个负电极化子和一个三重态激子的碰撞过程.结果表明,碰撞后体系仍保持为极化子和三重态激子状态的几率最大,束缚在极化子缺陷中的电子有较大的几率被激发到导带形成自由电子,另外,三重态激子有一定的几率被极化子湮灭形成极化子激发态.极化子和激子的碰撞对极化子的稳定性有影响,还会使能隙中出现新的能级.由于极化子激发态可以通过辐射跃迁回到基态,因此碰撞会对高聚物的电致发光效率产生一定影响.研究结果对于理解高聚物中极化子的输运性质和高聚物的发光性质具有一定的
关键词:
极化子
激子
高聚物 相似文献
9.
Effects of polarons on static order hyperpolarizabilities polarizabilities and second of conjugated polymers 下载免费PDF全文
According to the one-dimensional tight-binding Su-Schrieffer-Heeger model, we have investigated the effects of charged polarons on the static polarizability, axx, and the second order hyperpolarizabilities, γxxxx, of conjugated polymers. Our results are consistent qualitatively with previous ab initio and semi-empirical calculations. The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives. Furthermore, combining the Su Schrieffer-Heeger model and the extended Hubbard model, we have investigated systematically the effects of electron-electron interactions on αxx and γxxxx of charged polymer chains. For a fixed value of the nearest-neighbour interaction V, the values of αxx and γxxxx increase as the on-site Coulomb interaction U increases for U 〈 Uc and decrease with U for U 〉 Uc, where Uc is a critical value of U at which the static polarizability or the second order hypcrpolarizability reaches a maximal value of αxx or γxxxx. It is found that the effect of the e-e interaction on the value of αxx is dependent on the ratio between U and V for either a short or a long charged polymer. Whereas, that effect on the value of γxxxx is sensitive both to the ratio of U to V and to the size of the molecule. 相似文献
10.
The migration of a polaron at polymer/polymer interface is believed to be of fundamental importance for the transport and light-emitting properties of conjugated polymer-based light emitting diodes. Based on the one- dimensional tight-binding Su-Schrieffer-Heeger (SSH) model, we have investigated polaron dynamics in a one- dimensional polymer/polymer system by using a nonadiabatic evolution method. In particular, we focus on how a polaron migrates through the conjugated polymer/polymer interface in the presence of external electric field. The results show that the migration of polaron at the interface depends sensitively on the hopping integrals, the potential barrier induced by the energy mismatch, and the strength of applied electric field which increases the polaron kinetic energy. 相似文献