The Collision Process Of Oppositely Charged Trions In Polymers

Organic conjugated polymer is a new type of organic polymer materials with great potential development,it is not only can be conductive and luminous,but also have the advantages of high flexibility,easy processing,low price,which makes the organic materials become a research focus in recent years.Most of polymers are quasi-one-dimensional systems with strong electron-phonon interactions.Their carriers are composite particles,which are different from simply electron and hole,characterized with the surrounding distortion of lattice configuration,such as polaron,bipolaron and trion etc.These quasi particle systems have abundant physical process,such as the process of dynamic formation,excitation,collision and so on,These dynamic properties are believed to be of fundamental importance for electroluminescence properties.Some studies have shown that some elementary excitations,such as polaron,bipolaron and exciton,will generate of excited polaron(trion)through collision,excitation and composite processes.In this paper,based on one-dimensional tight-binding Su-Schrieffer-Heeger(SSH)model and by using a nonadiabatic molecular dynamic method,we investigated the collision process of oppositely charged trions in polymers.1.The collision process of oppositely charged trions on an isolated single polymer chainUnder the effect of the electric field,the oppositely charged trions can collide into singlet exciton,biexciton and trion states on an isolated single polymer chain.Under electric fields of strength(E<1.5mV/?),after the collision of the properties of oppositely charged trions,the formation yield of the exciton and biexciton have certain fluctuations with the change of electric field.With the increase of the electric field(1.5mV/? <E<4.0mV/?),the yields of the exciton and biexciton will be Increased.Under effect of more strong electric fields(E>4.0mV/?),since the collisions will cause the lattice vibrations,they may no longer have the regular lattice structures,and the charge becomes free particle.2.The collision process of oppositely charged trions on two coupled polymer chainsThe results of the dynamics of oppositely trions on two coupled polymer chains show that : If it is smaller interchain interactions,the oppositely trions return with primitive charge after collision under the driven of an external electric field.As the interchain interactions increases,the overlap of oppositely charges waves increase,the charges of positive and negative trions decrease gradually,they are a pair of independent particles and each of them is a mixture of excition,biexcition and trion.Continue to increase the coupling interactions,The collision causes a strong lattice vibration,the trions will dissociate and breakup,the charges will and not be localized in the regular self-trapping structure.Coupling area of interchain has also an effect on yield of excition and biexcition.With the increase of interchain coupling area,it has an effect on the overlap of positive and negative trions waves.The bigger coupling area is,the more the overlap of waves is.Therefore,charge transition is easier,and the yield of excition and biexcition is increased.