Saha Chowdhury Paramita, Patra Amitava
Sol-Gel Division, Central Glass & Ceramic Research Institute, Jadavpur, Kolkata, 700 032, India.
Phys Chem Chem Phys. 2006 Mar 21;8(11):1329-34. doi: 10.1039/b517788j. Epub 2006 Feb 2.
Here, we report the role of dopant concentration and surface coating of CdS: Eu3+ nanocrystals on the modification of crystal structure and their photoluminescence properties by steady-state and time resolved fluorescence studies. It is found that photoluminescence properties are sensitive to the crystal structure which is controlled by surface coating and dopant concentration. The emission intensity of the peak at 614 nm (5D0 --> 7F2) of the Eu3+-ions is found to be sensitive to the doping and surface coating of CdS nanocrystals. It is found that the average decay times tau are 248, 353 and 499 micros for 0.25, 0.5 and 1.0 mol% Eu ions doped into CdS nanocrystals, respectively. From the decay time measurements, it is evident that the energy transfer occurs from CdS nanoparticles to Eu3+ ions and the calculated energy transfer efficiency from CdS nanoparticles to Eu3+ ions is 9.2 and 35% for Eu3+ ions coated and doped CdS nanoparticles, respectively. Our analysis suggests that site symmetry of ions plays a very important role in the modifications of radiative and nonradiative relaxation mechanisms.
在此，我们通过稳态和时间分辨荧光研究报告了CdS:Eu3+纳米晶体的掺杂浓度和表面涂层对晶体结构改性及其光致发光特性的作用。研究发现，光致发光特性对由表面涂层和掺杂浓度控制的晶体结构敏感。发现Eu3+离子在614 nm（5D0 --> 7F2）处的峰发射强度对CdS纳米晶体的掺杂和表面涂层敏感。研究发现，分别向CdS纳米晶体中掺杂0.25、0.5和1.0 mol% Eu离子时，平均衰减时间τ分别为248、353和499微秒。从衰减时间测量结果可以明显看出，能量从CdS纳米颗粒转移到Eu3+离子，对于表面涂层和掺杂Eu3+离子的CdS纳米颗粒，从CdS纳米颗粒到Eu3+离子的计算能量转移效率分别为9.2%和35%。我们的分析表明，离子的位对称性在辐射和非辐射弛豫机制的改性中起着非常重要的作用。
