Probing photoinduced electron-transfer in graphene–dye hybrid materials for DSSC

Abstract

We investigated the photophysical properties of a newly synthesized hybrid material composed of a triphenylamine dye covalently bound to reduced graphene oxide, potentially relevant as a stable photosensitizer in dye-sensitized solar cells. The photophysical characterization has been carried out by means of fluorescence quenching and fluorescence lifetime measurements, complemented by Electron Paramagnetic Resonance (EPR) spectroscopy, aimed at the detailed description of the photoinduced processes occurring in the hybrid and in the mixed hybrid/N-doped TiO material. The combined optical/magnetic study unequivocally demonstrates a fast quenching of the dye excited state in the isolated hybrid and an efficient electron transfer to N-doped titania nanopowders. In the latter case, a metastable radical cation on the dye moiety is photogenerated and the corresponding negative charge, an electron, is trapped in defect sites of the doped semiconductor oxide. The spin distribution in the stable radical has been determined by EPR spectroscopy and correlated with DFT calculations.

Photophysical and Electrochemical Studies of Anchored Chromium (III) Complex on Reduced Graphene Oxide via Diazonium Chemistry

“…The doublet at 2922 cm −1 and 2859 cm −1 illustrate the asymmetric and symmetric alkyl chains of TMSPA. The vibrational bands of stretching and bending –NH 2 groups are at 3497 cm −1 and 1564 cm −1 respectively . The peaks at 1106 cm −1 and 1019 cm −1 correspond to the Si‐O‐Si and Si‐O‐C, confirms the silane coupling of rGO .…”

“…Modification of materials by diazonium chemistry also provides a well‐defined pathway to design and tune the optical properties for polymers fillers, polymer nanocomposites and polymer sensing layers. This also offers explicit routes to manipulate the nanorobots for cancer probes and drug delivery . Diazonium modification on graphene frame work appears promising since it results in significant increase of room temperature resistance and optical band gap of ~380 meV based on angle resolved photoemission electron microscopy measurements which leads graphene oxide as a potential material in optoelectronics .…”

“…This also offers explicit routes to manipulate the nanorobots for cancer probes and drug delivery. [19,[23][24][25][26][27][28][29][30][31][32][33][34] Diazonium modification on graphene frame work appears promising since it results in significant increase of room temperature resistance and optical band gap of~380 meV based on angle resolved photoemission electron microscopy measurements which leads graphene oxide as a potential material in optoelectronics. [35][36][37] There are reports on functionalization of GO with highly conjugated aromatic molecules, polymers and ionic electrolytes.…”

Interfacial Morphology Addresses Performance of Perovskite Solar Cells Based on Composite Hole Transporting Materials of Functionalized Reduced Graphene Oxide and P3HT

“…Unfortunately, this does not often occur due to the stronger tendency of pristine GBMs to self‐aggregate, as it happens for the majority of CNSs, compromising the homogeneity of their dispersion within a polymer matrix . In this regard, resorting to chemical functionalization of pristine CNSs can be useful when the process is sufficiently controllable to avoid an excessive disruption of the native electronic structure . In the past, we have applied a coupled covalent chemical functionalization/sedimentation‐based separation (SBS) strategy to obtain homogeneous dispersion of RGO in a P3HT matrix .…”

“…[1] In this regard, resorting to chemical functionalization of pristine CNSs can be useful when the process is sufficiently controllable to avoid an excessive disruption of the native electronic structure. [1,[34][35][36] In the past, we have applied a coupled covalent chemical functionalization/ sedimentation-based separation (SBS) strategy to obtain homogeneous dispersion of RGO in a P3HT matrix. [29] The chemical functionalities selected for binding to the RGO flakes surface were the 4-(methoxy)phenyl groups (thus leading to species named as RGO-PhOMe), introduced through a Tour-type direct arylation reaction [37] and previously demonstrated to be able to improve dispersibility of other CNSs in organic solvents and polymers.…”