【作者】 李欣；

【导师】 马凤英； 胡永生；

【作者基本信息】 郑州大学 ， 光学， 2025， 硕士

【摘要】 碳点(Carbondots,CDs)是一种零维碳纳米材料,由分散的类球状碳颗粒组成,尺寸通常小于10 nm。碳点具备出色的荧光特性、优良的水溶性、低毒性、制备简便以及低成本等优势,因而在生物医学成像、光催化、全息显示和光电子器件等领域得到了广泛应用。尽管碳点的研究已经取得了一定进展,但目前该领域仍面临两大核心挑战:一是缺乏统一的理论框架解释其荧光起源,这严重阻碍了对碳点性能的精确调控与优化;二是固态碳点普遍存在的聚集诱导淬灭(ACQ)问题,该问题极大地限制了碳点在固态激光、固态显示等领域的发展。本文从固态和液态两个维度出发,研究了碳点的受激辐射特性及其内在机制。同时涵盖了碳点在溶液态和固态两种状态下的激光特性,并研究了固态碳点电致发光特性,扩展了其在光学领域的应用潜力。这些结果为碳点在微型化激光器和柔性光电传感器等领域的应用奠定了坚实的理论与技术基础。本文旨在构建更加完善的碳点性能调控体系,推动碳点在光电材料领域的进一步发展。主要工作如下:1.碳点的受激辐射机制研究方面,本文详细探究碳点在受激辐射过程中的载流子复合动力学,通过稳态光致发光和时间分辨(TRPL)动力学技术,结合载流子动力学模型,系统研究了不同聚集程度碳点溶液的受激辐射特性。结果表明,碳点的聚集程度对碳点的光致发光量子产率(PLQY)、荧光峰位以及激光阈值产生了显著的影响,但它并不改变其内部载流子复合路径。碳点内部载流子主要复合路径是激子复合,聚集程度的改变会明显影响载流子复合动力学过程。随着聚集程度的降低,激子发射速率增大,激子-激子湮灭速率减小,从而导致辐射效率提升,最终降低激光阈值。这一发现不仅加深了我们对碳点的受激辐射机制的理解,还为开发高性能碳点增益材料和激光设备提供了指导。2.针对固态碳点中由ACQ效应引发的荧光效率降低问题,本文采用抗ACQ主客掺杂方法,制备了一系列重量分数介于0.5 wt%至90 wt%之间的固态碳点薄膜。结果显示,薄膜光致发光(PL)峰随重量分数的增加呈现逐渐红移的趋势。0.8wt%的薄膜展现出了的PLQY最高,达到21.2%。因此,进一步制备了一系列厚度范围在1.0至4.0 μm(均为0.8 wt%)的碳点薄膜,发现当薄膜厚度为2.2 μm时,其阈值达到最低,约为1.2 mJ/cm2。在此基础上,设计了一种基于表面等离激元(SPP)与分布式反馈(DFB)谐振腔的碳点固态激光器,成功实现了半峰宽(FWHM)小于1nm的多模激光输出。为进一步探索电泵浦激发的潜在应用,将0.5 wt%(呈现深蓝光)和0.8 wt%(呈现天蓝光)的抗ACQ薄膜集成到了电致发光二极管(LED)器件中,外部量子效率分别高达3.8%和2.7%。上述结果充分展示了碳点作为固态增益介质的巨大发展潜力和独特优势,有望在未来电泵浦激光器领域的发展进程中具有加速推动的潜力。本文研究了碳点的受激辐射机制,发现聚集程度对碳点的荧光量子产率和激光阈值有显著影响,为开发高性能碳点材料提供了理论基础。同时制备了高PLQY的固态碳点薄膜,通过优化薄膜参数及双光束光刻蒸镀旋涂等技术,制备出了固态碳点激光器,实现了窄半峰宽的激光输出。将抗聚集淬灭的碳点薄膜应用于LED器件,获得了较高的外部量子效率,充分展示了碳点在固态增益介质领域的巨大潜力,为固态碳点在光电器件中的应用提供了新视角和思路。更多还原

【Abstract】 Carbon dots(CDs)are zero-dimensional carbon nanomaterials consisting of dispersed spherical carbon particles,usually less than 10 nm in size,which are widely used in biomedical imaging,photocatalysis,holographic displays,and optoelectronic devices because of their excellent fluorescence properties,excellent water solubility,low toxicity,ease of preparation,and low cost.Although some progress has been made in the research of CDs,the field is still facing two core challenges:the lack of a unified theoretical framework to clearly explain the origin of their fluorescence,which seriously hampers the precise regulation and optimization of their properties;and the aggregation-caused quenching(ACQ)problem,which is common to solid-state CDs,which greatly restricts the development of CDs in specific solid-state applications,such as solid-state illumination and solidstate display.Applications such as solid-state lighting and solid-state display.In this paper,the excited radiation properties of CDs and their intrinsic mechanisms are investigated in depth from two dimensions:solid state and liquid state.It also covers the lasing properties of CDs in both solution and solid states and investigates the electroluminescence properties of CDs,which extends their potential applications in optics.These results lay a solid theoretical and technological foundation for the application of CDs in miniaturized lasers and flexible optoelectronic sensors.This thesis aims to construct a perfect system to regulate the properties of CDs and to promote the further development of CDs in the field of optoelectronic materials.The main work is as follows:1.As for the study of the excited radiation mechanism of CDs,this paper explores in detail the luminescence mechanism of CDs in the process of excited radiation and systematically investigates the excited radiation characteristics of CDs solutions with different aggregation degrees through steady-state photoluminescence and time-resolved photoluminescence(TRPL).The nature of the excited radiation of CDs is also deeply analyzed by combining it with the carrier kinetic model.The results show that although the degree of aggregation of CDs does not change their internal carrier complex paths,it has a significant effect on the highest photoluminescence quantum yield(PLQY),fluorescence peak position,and laser threshold of CDs.The internal carrier complex paths of CDs are mainly complexed by excitons.At different aggregation levels,the increase in aggregation significantly affects the process of carrier recombination dynamics.The exciton dynamics is affected.With the rise of the aggregation level,the exciton emission rate decreases,and the exciton-exciton annihilation(EEA)rate increases,which leads to the decrease of the radiation efficiency and ultimately to the rise of the lasing threshold.This finding not only deepens our understanding of the luminescence mechanism of CDs but also guides the development of highperformance carbon dot gain materials and laser devices.2.To address the problem of reduced fluorescence efficiency in solid-state CDs triggered by the ACQ effect,an innovative strategy,i.e.,the use of an anti-ACQ hostguest doping method,is adopted in this paper to successfully prepare a series of carbon dot films with weight fractions ranging from 0.5 wt%to 90 wt%.The experimental results show that the photoluminescence(PL)peaks of these films exhibit a gradual redshift with the increase of weight fraction,and it is particularly noteworthy that the 0.8 wt%film exhibits the PLQY.Therefore,we deeply further prepared CDs films with thicknesses ranging from 1.0 to 4.0 μm(all 0.8 wt%)and found that,when the film thicknesses are 2.2 μm,the threshold reaches their lowest value,which is about 1.2 mJ/cm2.On this basis,we designed a carbon dot solid-state laser based on a distributed feedback(DFB)resonant cavity with surface-isolated excitations,which possesses anti-aggregation quenching characteristics and successfully achieves a multimode laser output with a full width at half maximum(FWHM)of less than 1 nm.To further explore the potential applications of electrically pumped excitation and its effect on the luminescence properties of solid-state CDs,we integrated 0.5 wt%(presenting deep blue light)and 0.8 wt%(presenting sky blue light)ACQ-resistant thin films into electroluminescent diode(LED)devices,and the obtained external quantum efficiencies were as high as 3.8%and 2.7%,respectively.The great development potential and unique advantages of CDs as a solid-state gain medium are fully demonstrated,foreshadowing their potential to accelerate the development process in the field of electrically pumped lasers in the future.This study not only provides new perspectives and ideas for the application of solid-state CDs in optoelectronic devices but also opens up a new direction for research in related fields.In this thesis,the excited radiation mechanism of CDs is investigated,and the degree of aggregation is found to have a significant effect on the fluorescence quantum yield and lasing threshold of CDs,which provides a theoretical basis for the development of high-performance carbon dot materials.Meanwhile,a series of CDs films with high PLQY were successfully prepared by innovatively adopting the anti-aggregation quenching strategy,and a solid-state laser based on a surface-isolated exciton resonant cavity was designed by optimizing the parameters of the film to achieve a narrow halfpeak width laser output.In addition,the anti-ACQ CDs films were applied to LED devices,and high external quantum efficiencies were obtained,which fully demonstrated the great potential of CDs in the field of solid-state gain media,and provided a new idea for the further application of solid-state CDs in optoelectronic devices.更多还原