Interactions in GO/P3HT Layered Nanostructures: Spectroscopic Investigation for Organic Solar Cells

Herein, a simple and effective approach has been followed to deposit poly (3-hexylthiophene) (P3HT) and GO/P3HT layered nanostructures and fabricate their devices. Different structural, morphological, spectroscopic and electrical techniques were used to probe P3HT and GO/P3HT layered nanostructures properties. The X-ray diffraction (XRD) spectrum of GO/P3HT revealed a highly crystalline reflection of GO which is slightly shifted to higher diffraction angles as evidence of interaction with P3HT. As a proof of concept of interactions, the smooth surface morphology of P3HT translated to wrinkled structure for GO/P3HT presenting the existence of GO sheets in scanning electron microscopy (SEM). Fourier Transform Infrared spectroscopy (FTIR) confirmed the alteration of P3HT structure upon interaction with GO where the average conjugation length decreased from ~ 1.20 to ~ 1.12. The UV/VIS/NIR spectrum of GO/P3HT has an observable decrease in percentage reflectance leading to enhancement of the light absorption ability of P3HT with the inclusion of GO nanostructures. Furthermore, the bandgap energy decreased and resulted in a decrease in energetic driving force. The fluorescent decay curves revealed a decline in exciton lifetime depicting quicker charge transfer from P3HT to GO which resulted in a decrease in exciton diffusion length. Our findings suggest that the energetic driving force induced the mechanism involved during chemical interaction at the GO/P3HT interface. However, the calculated energetic driving force suggests that the interface between GO/P3HT be tuned, which agrees with J-V results where the GO/P3HT device revealed a low power conversion efficiency (PCE) of 3.07 %.