الفهرس 
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Abstract
We have synthesized different carbazole-based heterocyclic compounds M1-19 for DSSCs application. Their chemical structures were confirmed by the different elemental and spectral analysis. Moreover, theoretical calculation confirmed that all structures possessing all the thermodynamic requirements to be used for DSSCs. • Knoevenagel condensation of N-ethylcarbazole-3-carbaldehyde (3) with these cyanoacetanilide derivatives 4a-d in ethanol with a catalytic amount of piperidine produced the corresponding carbazolyl-cyanoacrylamide dyes M1-4. The corresponding carbazolyl-pyridone dyes M5-8 were picked up by the reaction of the carbazolyl-cyanoacrylamide derivatives M1-4 with malononitrile in boiling ethanol in the presence of piperidine. • Knoevenagel condensation of N-ethylcarbazole- 3-carbaldehyde (3) with various substituted thiazolidine-5-one derivatives (6a-h) to give (M9-16). • extension the conjugation in the acceptor structure by synthesis of different cyanoacetanilide derivatives 9a, 7 and 8. Then Knoevenagel condensation reaction of the former derivatives with compound 3 afforded our target dyes M17-19. all the dyes were applied for DFT/TD-DFT for the application of dye-sensitized solar cell. Interestingly, from the data, we found that all the dyes possess the thermodynamics for DSSC application, All HOMOs located below the redox potential of the electrolyte (-5.2 eV), while all LUMOs exists above the conduction band of the TiO2 edge (-4.2 eV). This behavior illustrates good charge transfer through the cell led to high performance of the fabricated devices. Further, we have studied the effect of co-sensitization of the promising dye (M4) along with the standard dye N-719. The photovoltaic studies revealed that 0.2 mM concentration of the co-sensitizer M4 enhances the light harvesting ability of the standard dye N-719. Additionally, we studied the effect of the cyclization of acrylamides (M1-4) with malononitrile to 2-pyridone moieties (M5-8) on the photovoltaic performances. In general, the cell based on the carbazolyl-cyanoacrylamide dyes M1-4 outperformed the carbazolyl-pyridone dyes M5-8 in terms of photovoltaic performance, which can be attributed to improved electron delocalization in the π-conjugated molecules when cyanoacrylamide moiety present in the molecular structure, leading to better light harvesting ability, improved JSC values.