| 초록 |
Intermolecular interactions have a critical role in determining the molecular packing and orientation of small molecule, leading to significant changes in their electrical and optical properties. Herein, we present two π–conjugated small molecules for use in solution-processed organic solar cells (OSCs) to elucidate the effect of terminal donor groups on the performance of benzodithiophene (BDT) based small molecules. Each small molecules have different terminal donor groups of hexyl-bithiophene (BDT(TTBT)2) or hexylphenyl-thiophene (BDT(PTBT)2). Various investigations into the molecules reveal that variation of the terminal groups not only influence the optical and electronic properties but also affect crystallization and morphology of the small molecules. BDT(TTBT)2 shows efficiency of 1.73% as a consequence of deep HOMO (Voc =0.81 V), improved charge delocalization and stronger light absorption (Jsc=4.75 mA/cm-2), when mild annealing was used as a result of improved texturing structures in morphology. BDT (PTBT)2 device rather shows moderate PCE of 1.22% with Jsc of 2.88 mA cm-2, Voc of 0.81V and FF of 0.52. |
