碳量子点发光波长拓展中的关键问题及其受激辐射特性研究

Carbon quantum dots is a new kind of fluorescent nano-materials. They attract more and more attentions due to their high efficient and broad excitation wavelength. However, a bottleneck, which is lack of high efficient long wavelength (i. e. red light longer than 600 nm) emission carbon quantum dots arises recently. Red light have wide applications in bio-imaging and laser areas. Most of previously reported carbon quantum dots were short wavelength emission carbon quantum dots. Few long wavelength emission carbon quantum dots, whose emission efficiency were much lower than that of short wavelength emission carbon quantum dots (as high as 99% for short wavelength emission carbon quantum dots) were reported. The primary reason is the vague emission mechanism of long wavelength emission carbon quantum dots..In this proposal, we will investigate two key factors: effect of conjugated sp2 domain and nitrogen doping of carbon quantum dots. Systematic study the influence of these two factors on long wavelength emission will be conducted and long wavelength emission mechanism from carbon quantum dots will be proposed. Based on the emission mechanism, high efficient long wavelength emission carbon quantum dots will be fabricated. Further investigation on stimulated emission from high efficient long wavelength emission carbon quantum dots will be conducted. Ultra low threshold red light laser and whispering gallery modes laser from high efficient long wavelength carbon quantum dots will be realized. This research will provide theoretical and experimental support on application of carbon quantum dots in red light areas and lasers.

碳量子点是一种新型的纳米发光材料，其发光效率高，激发适应性好等特性使其倍受关注。但目前碳量子点的发光研究遇到了一个瓶颈：波长拓展问题。即，高效长波（大于600nm的红光）发光碳量子点的缺失。红光在生物成像和激光领域有着更广泛的应用。但目前报道的多数都是短波发光的碳量子点，少数几篇文献报道过长波发光碳量子点，但发光效率仍然无法与短波发光碳量子点高达99%的发光效率相媲美。究其根源是学术界对长波发光碳量子点的发光机理仍然不清楚。.本项目拟从影响碳量子点长波发光的两个关键因素：共轭sp2结构和氮元素掺杂对碳量子点长波发光的影响入手，系统研究这两因素对碳量子点长波发光的影响，从而理解碳量子点长波发光机理，并用于指导制备高效长波发光碳量子点。并进一步研究碳量子点的长波受激辐射特性，实现碳量子点超低阈值红光激光发射和不同腔体的回音廊模式红光激光。这将为碳量子点在红光和激光领域的应用提供理论和实验支持。

碳量子点是一种新型的纳米发光材料，其发光效率高，激发适应性好等特性使其倍受关注。但目前碳量子点的发光研究遇到了一个瓶颈：波长拓展问题。即，高效长波（大于600nm的红光）发光碳量子点的缺失。红光在生物成像和激光领域有着更广泛的应用。但目前报道的多数都是短波发光的碳量子点，少数几篇文献报道过长波发光碳量子点，但发光效率仍然无法与短波发光碳量子点高达99%的发光效率相媲美。究其根源是学术界对长波发光碳量子点的发光机理仍然不清楚。.本项目着重从元素掺杂对碳量子点长波发光的影响入手，系统研究元素掺杂量和不同的元素掺杂对碳量子点长波发光的影响，提出了氧元素掺杂对长波发光的影响机理，并指导制备了发光峰值波长介于600-650nm之间的高效长波发光碳量子点。长波发光碳量子点发光效率达到80%以上。在此基础上我们进一步研究碳量子点的长波受激辐射特性，通过合理的碳量子点增益介质选择和低损耗激光腔体设计实现碳量子点超低阈值红光激光发射，产生激光的阈值峰值功率约为70W/cm-2.并在16-65 微米尺寸之间均实现了碳量子点回音廊模式红光激光发射，最小回音廊模式激光器尺寸约为16微米。完成了项目预期目标。