In this study we report on a series of 12 small molecular p-type penta- and hexathiophene semiconductors end-capped with either malononitrile (MN), hexyl rhodanine (HR) or dicyano hexyl rhodanine (CHR) acceptors and functionalized with alkyl sidechains of two different lengths, orientated away from the central core in a regioregular manner. Organic photovoltaic devices were fabricated, and annealed using conditions optimized for each material to produce a wide range of power-conversion efficiencies (PCEs) from 1–8%. We find that achieving high PCEs is critically dependent on matching the conjugation length to specific end-group acceptors, and also find a slight correlation between improved performances and longer sidechains. To understand this behavior we performed an in-depth analysis of the structure–property relationships of these materials on intermolecular packing through grazing-incidence wide-angle X-ray scattering (GIWAXS) studies, which yielded several key relationships between molecular structure, bulk crystallinity and optoelectronic properties.

中文翻译：

---

p型A–D–A寡噻吩的结构研究：区域规则的烷基侧链对退火过程和光伏性能的影响†

在这项研究中，我们报告了一系列12个由丙二腈（MN），己基若丹丹（HR）或二氰基己基若丹丹（CHR）受体封端并被两个烷基侧链官能化的12个小分子p型五和六噻吩半导体不同的长度，以区域规则的方式远离中心核心定向。制造有机光伏器件，并使用针对每种材料优化的条件进行退火，以产生1％至8％的宽范围的功率转换效率（PCE）。我们发现实现高PCE关键取决于将缀合长度与特定的端基受体匹配，并且还发现改进的性能和更长的侧链之间存在轻微的相关性。