Study On Preparation And Performance Of Novel Organic Lasers Based On Field-effect Transistor Structures

Organic semiconductor lasers have become the focus of increasing research activity in the optoelectronic field since organic materials possess the great advantages of facile preparation,low cost and tunable characteristics.Although optically-pumped organic lasing has been developed maturely,the electrically-pumped organic lasers have not been achieved yet.Among three key elements in organic lasers,the incorporation of resonators remains a great challenge in the current study and needs to be more deeply investigated.In order to tackle the problems such as the complicated processes of the preparation of resonators and the low yields,novel optoelectronic devices have been achieved with the introduction of resonators into organic field-effect transistors to systematically investigate the fabrication methods,multifunctional integration,light amplification and charge transport.It can provide a new idea of realizing electrically-pumped organic lasers.Specifically,with a combination of resonators,optical pumping and OFET,the organic laser devices based on distributed feedback(DFB)structures have been constructed in the thesis,providing a deep insight into the lasing properties,electrical characteristics and related mechanisms.Main studies are summarized as follows:(1)Novel optoelectronic devices for achieving electrically-pumped organic lasers have been designed and fabricated based on OFET structures.The incorporation of DFB into the flexible transparent dielectric layer of OFETs can address the issue of the difficulty of introducing resonators into electrically-pumped organic lasers.Meanwhile,the device can possess good lasing properties and OFET characteristics.The PDMS dielectric layer with appropriate thicknesses and superior optoelectronic characteristics can be obtained and integrated into DFB structures by adjusting the solvent,substrate,spin-coating speed,curing temperature and UV-O₃ time.This work has provided the possibility of achieving electrically-pumped organic lasers by means of employing the dielectric layer in OFETs,which can demonstrate a new perspective for the design and innovation of organic lasers.(2)The ASE and lasing characteristics of OFETs with the novel dielectric layer have been investigated in details.DFB-OFET devices can be fabricated via both vacuum vapor deposition and solution methods,demonstrating good optical feedback and lasing properties,which indicates that the device preparation is applicable for most organic gain media.BSBCz has the lasing threshold of27.9?J/cm²(5.33 n J/pulse)with the lasing wavelength of 479 nm;the lasing threshold of 27.9?J/cm²(5.33 n J/pulse)with the lasing wavelength of 479 nm is observed for F8BT.In this case,the transparent dielectric layer can effectively suppress the electrode quenching and realize optical feedback,offering important experimental foundation for electrically-pumped organic lasers.(3)Taking TIPS and PBTTT-C14 as examples,the influence of the dielectric layer thickness,the grating direction and the grating period on the electrical properties of DFB-OFET devices has been fully explored.Meanwhile,the relationship between the film morphologies on the grating,the fabrication methods and OFET characteristics has also been deeply investigated.In DFB-OFET devices,organic semiconductors can grow with a certain orientation in the case of space constraints,which can greatly improve the charge transport behavior.Therefore,the mobility of OFET with DFB grating structures is higher than that without DFB grating structures.This kind of devices can possess the advantages of flexibility,transparency,simply operation and stable performance,which will have great potential in multifunctional integration organic lasers in the future.