New aliphatic–aromatic tetraphenylphthalic-based diimides: Thermal, optical and electrical study

The thermal and opto-electrical properties of new thermotropic compounds based on tetraphenylphthalic-based imides have been explored. Energy band gap (Egopt.) was calculated from absorption spectrum and absorption coefficient α. Current–voltage (I–V) measurements were performed on ITO/compound/Al, ITO/compound:PCBM/Al and ITO/PEDOT:PSS/compound:PCBM/Al devices before and after irradiation with light (under illumination 1000 W/m2). Compounds were blended with [6,6]-phenyl C61 butyric acid methyl ester (PCBM) in the weight ratio 1:1 and additionally tested using various AFM techniques. The mesogenic properties were characterized by POM and DSC. Both compounds exhibited liquid crystalline properties. Preliminary photovoltaic experiments were carried out for two kinds of bulk heterojunction devices (BHJ) and compared with reference device. For the first time, to the best our knowledge, tetraphenylphthalic-based imides with liquid crystalline properties were examined and described in the article.

Graphical abstractThe thermal and opto-electrical properties of new thermotropic compounds based on tetraphenylphthalic-based imides have been explored. Both compounds exhibited liquid crystalline properties. The new LC imides were applied for construction of devices with various architectures: ITO/compound/Al, ITO/compound:PCBM/Al and ITO/PEDOT:PSS/compound:PCBM/Al. Preliminary photovoltaic experiments were carried and a photovoltaic effect was confirmed.Figure optionsDownload full-size imageDownload high-quality image (321 K)Download as PowerPoint slideResearch highlights► We obtained new thermotropic tetraphenylphthalic-based imides. ► We analyse mesomorphic behaviour in the level of structural changes. ► We examine devices with various architectures. The I–V effects depend on construction devices. ► We examine tetraphenylphthalic-based imides in photovoltaic experiments and a photovoltaic effect was confirmed.