Role of Spontaneous Orientational Polarization in Organic Donor–Acceptor Blends for Exciton Binding,Advanced Optical Materials

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Role of Spontaneous Orientational Polarization in Organic Donor–Acceptor Blends for Exciton Binding
Advanced Optical Materials ( IF 8.0 ) Pub Date : 2020-09-03 , DOI: 10.1002/adom.202000896
Yuuhi Ueda ₁ , Hajime Nakanotani _{1,

2,

3} , Takuya Hosokai ₄ , Yuya Tanaka _{5,

6} , Hokuto Hamada ₆ , Hisao Ishii _{5,

6} , Shuhei Santo ₄ , Chihaya Adachi _{1,

2,

3}

Affiliation

Electron–hole pairs at the interface between electron‐donating and electron‐accepting molecules form charge‐transfer excitons (CTEs) via Coulomb attraction. Generally, the attraction energy of the CTE is weaker than that of the Frenkel exciton because of spatial separation of the charge pair; thus, the binding of the CTE is expected to be sensitive to an electric field. Here, the shielding of the binding energy of the CTEs by an internal electric field induced by spontaneous orientation polarization (SOP) of the solid‐state donor–acceptor blend film is reported. When the blend film forms a large SOP, the photogenerated CTEs spontaneously dissociate without an external electric field, resulting in carrier diffusion and carrier lifetimes that are in the milliseconds or longer. In the absence of a large SOP, the CTEs preferentially form exciplexes that quickly release their energy as light rather than dissociation. Hence, the control of SOP in the donor–acceptor blend films can provide new insights into exciton binding and facilitate the development of tailored high‐performance organic semiconductor devices.

中文翻译：

自发取向极化在激子结合的有机供体-受体混合物中的作用

供电子分子与受电子分子之间的界面上的电子-空穴对通过库仑吸引形成电荷转移激子（CTE）。通常，由于电荷对的空间分隔，CTE的吸引能比Frenkel激子的吸引能弱。因此，期望CTE的结合对电场敏感。此处报道了固态施主-受体共混膜的自发取向极化（SOP）引起的内部电场对CTE结合能的屏蔽作用。当共混膜形成较大的SOP时，光生CTE会自发解离而没有外部电场，从而导致载流子扩散和载流子寿命达到毫秒或更长。在没有大量SOP的情况下，CTE优先形成激基复合物，该激基复合物以光而不是离解的形式快速释放能量。因此，对施主-受主混合膜中SOP的控制可以提供对激子结合的新见解，并有助于开发定制的高性能有机半导体器件。

更新日期：2020-11-04

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