Study On Laser Performance Of Organic Semiconductor Material

Generally, organic semiconductor materials have a conjugate structure, their molecular structure can be designed to meet the need of function. Their emission spectra can cover the entire visible spectrum region. Organic excitons show a very good thermal stability. Organic materials have the characteristic of diversity of structure and abundant species, and are an important branch of the laser gain materials.Optically and electrically pumped lasers based on organic gain medium is one of the hot spot in the field of organic optoelectronics. Organic materials can form amorphous thin films through a variety of low-cost ways. They have low requirement to the substrate, and can be deposited on both rigid or flexible substrates. However, organic materials have weak molecular interaction forces, show bad stability. The material performance is very vulnerable to the temperature of the surrounding environment and the influence of oxygen and water vapor in the air. Therefore, encapsulation problems must be solved before practical application of organic optoelectronic devices, in order to prevent the material degradation. Organic semiconductor laser has many years of research history, but most of the materials have a high laser threshold, which is not conducive to the realization of the electrically pumped organic laser, and the study on stability of the laser performance is seldom reported. Therefore, the research and development of new organic laser materials, and the realization of low threshold and stable optically pumped organic lasers are the important basis for the development of organic laser technology. In this thesis, we carried out the following research work for the target.1. Amplified spontaneous emission (ASE) properties of BODIPY derivativesAs fluorescent dyes, BODIPY derivatives have high fluorescent efficiency and light stability. Their luminescent properties can be modified by the introduction of different molecular groups in their basic molecular structure. We studied the stimulated emission properties of phenyl, naphthyl and anthracene substituted BODIPY derivatives (PhBOD, NaBOD, and EnBOD). We found that they have good ASE performance in toluene, their ASE efficiency are more than 22%. Among them, the ASE threshold is about 99 kW·cm-2 at the concentration of 0.008 Mol·L-1 for the PhBOD toluene sample. The ASE intensity remains 80% of the initial value after 200000 pump pulses in the same position, which implies a very high photostability of the PhBOD material. Films of the three materials can be prepared by doping them into PS. When placed in the atmospheric environment after three months, the ASE thresholds of the PhBOD, NaBOD and EnBOD samples increased 2.99,2.85, and 3.76 times, respectively. Under the test condition of high temperature 100℃, the ASE thresholds of PhBOD, NaBOD and EnBOD samples were increased 1.88,4.94, and 5.41 times in comparison with the case of room temperature.2. The ASE properties of F-NI, TR-NI, and PY-NI materialsThese three kinds of materials are fluorene, three indene and pyrene derivatives with naphthalene imide group. The results show that they have not only good ASE performance, but also good thermal and environmental stability. Among them, the PS:F-NI thin film were tested under the condition of 200℃ high temperature environment, the sample can still maintain a lower ASE threshold, and ASE peak position shows no deviation, the threshold value is higher than the value at room temperature only 1.17 times. ASE threshold was nearly unchanged after the sample waw placed in air atmosphere for a year.3. New electronic injection layer material YF3Organic light emitting devices (OLEDs) were fabricated with yttrium fluoride (YF3), instead of lithium fluoride (LiF), as electron injection layer. The experimental results showed that YF3 injection buffer layer with appropriate thickness can effectively enhance the electron injection ability of the cathode, leading to more balanced concentration of electrons and holes, and optimized electroluminescent properties of OLEDs. The OLED with 1.2 nm-thick YF3 layer had the minimum turn-on voltage of 2.6 V, the maximum current efficiency of 8.52 cd·A-1, and the maximum luminance of 36530 cd·m-2. Compared with LiF reference sample, the maximum brightness and current efficiency were increased by 39% and 53%, respectively.4 Ontirally pumned organic miccrocavity lasers at 650 nm Organic microcavity structures were designed and fabricated with distributed Bragg reflector as the mirror, and Alq3 DCJTI host-guest doping system as the gain medium. The standing wave field within microcavity was simulated by using the transfer matrix method, and a suitable microcavity structure was determined. The lasing properties of the microcavity laser were studied by a UV pulse laser. The output wavelength of the microcavitv laser is 650 nm. An obvious las ins:behavior was observed with a threshold intensity of 110 W·cm-2. The FWHM was.parrowed from 4.7 to 3.2 nm before and after the threshold.