Preventing crystallization of small donor molecules in organic photovoltaic cells

有机光伏电池含有由两种材料组成的本体异质结：电子供体和电子供体。 电子受体富勒烯衍生物是最常用的一类电子受体，因为 他们的高效率。在大多数情况下，电子供体是聚合物，因为它们可以容易地加工成 高质量的薄膜。小分子更容易纯化和表征，并给出更一致的结果 这是因为它们的离散性质，但易于结晶，导致颗粒状、质量差的薄膜。 该项目的目标是制定战略，将小分子用于捐助者和 有机PV电池中的受体材料。为了实现这一目标，开发可加工的材料至关重要 变成薄膜而不结晶。为此，可以使用能够在室温下进行化学反应的受体材料（其将保持恒定）。 形成非晶薄膜和用作各种小分子供体材料的非晶主体 将被设计和合成。 Lebel小组已经表明，一些mexylaminotriazine衍生物能够形成极其稳定的 玻璃相，而在延长的时间段内不结晶。这些化合物也可以化学 与各种发色团键合以产生加合物，所述加合物可以容易地形成无定形薄膜，并且它还 可以将这些材料与“常规”小分子混合以产生无定形混合物， 组分均匀分散。 因此，将合成并入mexylaminotriazine单元的玻璃形成富勒烯受体。在第一 步骤中，C60将根据公开的方法用含有羟基、氨基 或羧基，然后将与甲基氨基三嗪衍生物键合。 目标化合物将首先混合到各种小分子供体中，以确保高质量的薄 获得两种组分都适当分散的膜。有前途的混合物将被纳入 来评估它们的性能。

Organic photovoltaic cells contain a bulk heterojunction composed of two materials: an electron donor and an electron acceptor. Fullerene derivatives are the most commonly used class of electron acceptors because of their high efficiency. In most cases, electron donors are polymers, because they can be easily processed into high-quality thin films. Small molecules are easier to purify and characterize, and give more consistent results because of their discrete nature, but tend to crystallize easily, leading to grainy, poor-quality thin films. The objective of the project consists in developing strategies to use small molecules for both donor and acceptor materials in organic PV cells. To achieve this, it is crucial to develop materials that can be processed into thin films without crystallizing. To this end, an acceptor material (which will be kept constant) capable of forming amorphous thin films and of acting as an amorphous host for various small-molecule donor materials will be designed and synthesized. The Lebel group has shown that some mexylaminotriazine derivatives are capable of forming extremely stable glassy phases without crystallizing over extended periods of time. These compounds can also be chemically bonded to various chromophores to generate adducts that can readily form amorphous thin films, and it is also possible to blend these materials with "regular" small molecules to generate amorphous blends where both components are homogeneously dispersed. A glass-forming fullerene acceptor incorporating a mexylaminotriazine unit will thus be synthesized. In a first step, C60 will be functionalized according to published procedures with a moiety containing a hydroxy, amino or carboxy group, to which a mexylaminotriazine derivative will then be bonded. The target compounds will first be blended to various small-molecule donors to ensure that high-quality thin films are obtained where both components are properly dispersed. Promising blends will then be incorporated into photovoltaic cells to assess their performance.