Study On Organic Lasing

Wang zijun ( Condensed Matter Physics ) Directed by Prof. Zhong Guozhu and Li WenlianHotly studied organic thin film electroluminescence, because of its ultra high brightness and efficiency, reminds man to consider the possibility of realizing organic semiconducting laser diods. The first breakout has taken place on an organic single crystal by clever using a TET. Simultaneously, the big current needed for lasing also can pass through an organic thin film, showed by an experiment.Laser is one of rare beautiful Physical examples( their theories before their realizing), so its theory is very reliable. The main contents of the dissertation are in solving key technological problems, developing new laser dyes, and studying their lasing property: Effects of microcavity are very sensitive to their size. Controlling its constructing layers' thickness is an important technology. Through theoretical calculation, if occasional errors of all layers are accumulated in a Distributed Bragg Refiector(DBR), reflecting spectrum of the DBR will be changed heavily. It is pointed out here the method of optical extreme value is very reliable, because of its avoiding accumulation of errors. A method of getting effective microcavity length by measuring microcavity emitting modes, which can direct the controlling of thickness of organic layers, is put forward. Emissions from microcavitys made with organic materials with broad and sharp optical spectra were compared respectively, apparent microcavity effects appeared. Some new small mass molecule organic laser dyes with blue emitting color, were found. Lasing were realized with waveguide structure of some materials' films on glass substrate. ITO glass is a rare transparent electrode, and ever was considered to be used in organic microcavity laser diodes. But it may trap light because of its larger refrective index than usual organic materials. Can it be lasing on ITO just as on glass? Our experimental answer was positive. It was concluded that lasing was waveguided in ITO layer and amplified near the interface in lighting layer where gain was obtained by light pumping. In this amplifying way, lasing was firstly realized in an organic emitting diode in the area. The gain region was produced by light pumping through ITO side of the sample, and electrical injection was also applied. Important information is that the distance between metal electrode and emitting layer must be suitable. Too large, difficult injection; too small, excitons quenching. Within 0-70mA/cm2 injection, no effect was observed. More information will be found if a FET is introduced, because of its capability of large electrical injection.