Role of Hydroxyl Groups in the Photophysics, Photostability, and (Opto)electronic Properties of the Fungi-Derived Pigment Xylindein
Role of Hydroxyl Groups in the Photophysics, Photostability, and (Opto)electronic Properties of the Fungi-Derived Pigment Xylindein
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DOI：
10.1021/acs.jpcc.0c09627
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发表时间：
2021-03-18
影响因子：
3.7
通讯作者：
Ostroverkhova, Oksana
中科院分区：
文献类型：
--
作者：
Giesbers, Gregory;Krueger, Taylor D.;Ostroverkhova, Oksana
有机半导体由于其低成本、溶液可加工性和可调性质而引起越来越多的关注。特别感兴趣的是具有增强的环境稳定性的分子。我们最近报道了一个非常稳定的，天然衍生的色素木黄酮的（光）电子性质。在这里，我们确定木茚定的分子结构的一个特定方面，即羟基（OH）基团的存在，是使其增强的稳定性和相对较高的电子迁移率的关键。特别是，我们合成了一个甲基化的衍生物木茚定，二甲基木茚定，其中的OH基团被OCH 3基团取代，并比较了物理和（光）电子性质的二甲基木茚定和木茚定。我们揭示了一个长寿命的激发态在二甲基木茚定，木茚定，它有一个有效的快速非辐射途径的基态。这导致与木茚定相比，二甲基木茚定的光稳定性显著降低。有效的电子迁移率，从空间电荷限制电流，在非晶木茚定膜被发现是4个数量级高于非晶和结晶二甲基木茚定膜。相比之下，二甲基木茚定的光敏性比木茚定高约2个数量级。在所有的膜中的电荷传输的机制是热激活的跳跃，与xylindein膜的特征在于相当浅的电荷陷阱比二甲基xylindein膜，归因于氢键通过羟基促进有效的导电网络中xylindein。
Organic semiconductors have attracted increasing attention due to their low cost, solution processability, and tunable properties. Of special interest are molecules with enhanced environmental stability. We have recently reported on the (opto)electronic properties of a remarkably stable, naturally derived pigment xylindein. Here, we establish that one particular aspect of xylindein's molecular structure, namely the presence of hydroxyl (OH) groups, is critical for enabling its enhanced stability and relatively high electron mobility. In particular, we synthesized a methylated derivative of xylindein, dimethylxylindein, where the OH groups are replaced with OCH3 groups, and compared photophysics and the (opto)electronic properties of dimethylxylindein and xylindein. We reveal the presence of a long-lived excited state in dimethylxylindein, in contrast to xylindein, which has an efficient fast nonradiative pathway to the ground state. This results in significantly reduced photostability of dimethylxylindein as compared to xylindein. The effective electron mobility, obtained from space-charge-limited currents, in amorphous xylindein films was found to be 4 orders of magnitude higher than that in amorphous and crystalline dimethylxylindein films. In contrast, the photosensitivity of dimethylxylindein is about 2 orders of magnitude higher than that of xylindein. The mechanism of charge transport in all films was thermally activated hopping, with the xylindein films characterized by considerably shallower charge traps than dimethylxylindein films, attributed to hydrogen bonding via hydroxyl groups promoting an efficient conductive network in xylindein.