Herrera Christopher K, Vahdani Aria, Yang Chenchen, Bates Matthew, Lunt Sophia Y, Borhan Babak, Lunt Richard R
Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, United States.
Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States.
ACS Photonics. 2023 Sep 20;10(9):3195-3202. doi: 10.1021/acsphotonics.3c00602. Epub 2023 Aug 23.
Organic luminophores offer great potential for energy harvesting and light emission due to tunable spectral properties, strong luminescence, high solubility, and excellent wavelength-selectivity. To realize their full potential, the lifetimes of luminophores must extend to many years under illumination. Many organic luminophores, however, have a tendency to degrade and undergo rapid photobleaching, leading to the perception of intrinsic instability of organic molecules. In this work we demonstrate that by exchanging the counterion of a heptamethine cyanine salt the photostability and corresponding lifetime of dilute cyanine salts can be enhanced by orders of magnitude from 10 hours to an extrapolated lifetime of greater than 65,000 hours under illumination. To help correlate and comprehend the underlying mechanism behind this phenomenon, the water contact angle and binding energy of each pairing were measured and calculated. We find that increased water contact angle, and therefore increasing hydrophobicity, generally correlate to improved lifetimes. Similarly, a lower absolute binding energy between cation and anion correlates to increased lifetimes. Utilizing the binding energy formalism, we predict the stability of a new anion and experimentally verify with good consistency. Moving forward, these factors could be used to rapidly screen and identify highly photostable organic luminophore salt systems for a range of energy harvesting and light emitting applications.
由于具有可调谐的光谱特性、强发光性、高溶解性和出色的波长选择性，有机发光体在能量收集和发光方面具有巨大潜力。为了充分发挥其潜力，发光体在光照下的寿命必须延长至数年。然而，许多有机发光体往往会降解并迅速发生光漂白，导致人们认为有机分子具有内在不稳定性。在这项工作中，我们证明，通过交换七甲川菁盐的抗衡离子，稀菁盐的光稳定性和相应寿命可以提高几个数量级，从10小时延长至光照下推断寿命超过65000小时。为了帮助关联和理解这一现象背后的潜在机制，我们测量并计算了每种配对的水接触角和结合能。我们发现，水接触角增加，进而疏水性增加，通常与寿命延长相关。同样，阳离子与阴离子之间较低的绝对结合能与寿命增加相关。利用结合能形式理论，我们预测了一种新阴离子的稳定性，并通过实验得到了很好的验证。展望未来，这些因素可用于快速筛选和识别用于一系列能量收集和发光应用的高光稳定性有机发光体盐体系。
