Research On The Enhancement Of Organic Lasing Based On Plasma Effect And Perovskite Lasing Performance

In recent years,Organic semiconductors are attractive gain media for optoelectronic devices due to their good luminescence qualities,easy processing,and broad spectral emission range.Optically pumped lasers have been demonstrated in a wide range of materials with several different structures.Developing electrically pumped laser is an important topic.A metallic cathode needs to be included in the devices to inject electrons.However,the high absorption loss of metallic cathodes can increase the lasing threshold or even inhibit lasing.Metal nanoparticles play an important role in improving lasing properties via a plasmonic effect and strong scattering effect.As we known,lead halide perovskites are considered as very promising photovoltaic materials.With unique properties of perovskites materials,the lead halide perovskites have also demonstrated great potential for use as semiconductor gain materials.In this thesis,the amplified spontaneous emission characteristics of organic semiconductor lasing devices based on metal nanostructures and cesium lead bromide quantum dots are studied.The contents of this thesis are as follows:(1)The random lasing phenomenon based on the composite structure of gold silver core-shell nanorods and silver film(Au@Ag NRs-Ag film)is studied,which makes the lasing performance significantly enhanced.This study reveals that the Au@Ag NRs-Ag film hybrid structure can more effectively enhance the lasing properties than independent Au@Ag NRs or Ag film.Besides,compared with hybrid structures composed of Ag film with Au nanorods or Au nanospheres,the gain medium deposited on Au@Ag NRs-Ag film has the lowest lasing threshold:only 12.5%of that of the neat gain medium.As a unique plasmonic hybrid nanostructure,Au@Ag NRs-Ag film exhibits a stronger localized electrical field and scattering effect than the hybrid structures composed of Ag film with regular Au nanoparticles.This is attributed to the broader and stronger plasmonic absorption of Au@Ag NRs,as well as to the stronger plasmonic coupling between the localized surface plasmons of Au@Ag NRs and the delocalized surface plasmon polariton of Ag film.The thesis provides a simple way to effectively avoid the negative effects of metal films and realize a lower pumped threshold.(2)A dramatic threshold reduction is reported for random lasing based on a plasmonic hybrid structure of Au core-SiO2 shell nanocubes deposited on Ag film(Au@SiO2 NCs).This hybrid structure could more significantly lower the lasing threshold than Ag film or Au@SiO2 NCs.In particular,the SiO2 shell simultaneously tuned the interactions of localized surface plasmons(LSPs)of the Au NC cores with surface plasmon polariton(SPP)of the Ag film and gain medium.The optimal thickness of the SiO2 shell was determined that could result in the lowest lasing threshold:14.1%that of the neat gain medium.Furthermore,compared to a hybrid structure consisting of Ag film with regular metal nanoparticles,Au@SiO2 nanospheres,the gain medium based on Au@SiO2 NCs-Ag film hybrid structure had a lower lasing threshold.This was attributed to the stronger electric field and scattering of the Au NC than the Au nanosphere cores,thus ensuring a stronger plasma interaction between the SPP of the Ag film and the LSPs of the Au NC cores.The thesis provides a convenient method to lower the lasing threshold of the gain medium in the presence of metal film.(3)A double ligand post-treatment method is proposed to passivate the surface defects of CsPbBr3 quantum dots,and achieve a low-threshold amplified spontaneous emission.The surface of perovskite quantum dots usually has high defect density,which will lead to the poor luminescent and poor stability.Therefore,this thesis uses tetra-octane-bromoamine and PbBr2 to post-treatment of CsPbBr3 quantum dots to improve its optical properties and maintain its original crystal phase.The effect of passivation solution on the luminescent properties of CsPbBr3 quantum dot films was investigated.Finally,in order to further improve the stability of CsPbBr3 quantum dots,CsPbBr3 quantum dots are introduced into PMMA to encapsulate the quantum dots,thereby the perovskite quantum dot films with low threshold and high stability were realized.