Bhattacharyya Biswajit, Mukherjee Arpita, Mahadevu Rekha, Pandey Anshu
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
J Chem Phys. 2021 Feb 21;154(7):074707. doi: 10.1063/5.0036676.
Photonic devices stand to benefit from the development of chromophores with tunable, precisely controlled spontaneous emission lifetimes. Here, we demonstrate a method to continuously tune the radiative emission lifetimes of a class of chromophores by varying the density of electronic states involved in the emission process. In particular, we examined the peculiar composition-dependent electronic structure of copper doped CdZnSe quantum dots. It is shown that the nature and density of electronic states involved with the emission process is a function of copper inclusion level, providing a very direct handle for controlling the spontaneous lifetimes. The spontaneous emission lifetimes are estimated by examining the ratios of emission lifetimes to absolute quantum yields and also measured directly by ultrafast luminescence upconversion experiments. We find excellent agreement between these classes of experiments. This scheme enables us to tune spontaneous emission lifetimes by three orders of magnitude from ∼15 ns to over ∼7 µs, which is unprecedented in existing lumophores.
光子器件有望受益于具有可调谐、精确控制的自发发射寿命的发色团的发展。在此，我们展示了一种通过改变发射过程中涉及的电子态密度来连续调节一类发色团的辐射发射寿命的方法。特别地，我们研究了铜掺杂的CdZnSe量子点独特的成分依赖电子结构。结果表明，发射过程中涉及的电子态的性质和密度是铜掺入水平的函数，这为控制自发寿命提供了非常直接的手段。通过检查发射寿命与绝对量子产率的比率来估计自发发射寿命，并且也通过超快发光上转换实验直接测量。我们发现这些类型的实验之间具有极好的一致性。该方案使我们能够将自发发射寿命从约15纳秒到超过约7微秒调节三个数量级，这在现有的发光体中是前所未有的。
