Theoretical Studies on the Structure, Optoelectronic and Photosensitizer Applications of NKX Class of Coumarin Dye Molecules

Abstract

Coumarin based NKX class of molecules have been recently investigated for their promising sensitizing applications in dye Sensitized Solar Cells (DSSCs). However, the various factors limiting the sensitizing properties of these molecules such as charge transport efficiency and electron back recombination still remain to be understood properly. Herein, we report a detailed theoretical study on the structural, opto‐electronic and photo‐sensitizer applications of 2‐cyano‐3‐[5‐(1, 1, 6,6‐tetramethyl‐10‐oxo‐2,3,5,6‐tetrahydro‐1H,4H,10H‐11‐oxa‐3a‐aza‐benzo[de]anthracen‐9‐yl)‐thiophen‐2‐yl]‐acrylicacid (NKX 2587) based dye molecules. Structural variation of the dye molecule through derivatization has been attempted, with the main emphasis on the minimization of the back electron recombination rates through reduced dye – I2 interaction. The optical and photovoltaic properties of these dyes were studied in terms of the key parameters like, HOMO‐LUMO energy gap, maximum absorption wavelength, λmax, light harvesting efficiency, charge injection efficiency, open voltage, reorganization energy etc. using density functional theory methods. The results reflect that the dyes with more electron withdrawing substituents exhibit lower dye – I2 interaction, thus minimizing the back recombination. Moreover, the dyes with chloro (C3), bromo (C4), iodo (C5) and cyano (C7) substituents exhibit almost double electronic injection efficiency in comparison to the parent sensitizer molecule and are hence, expected to enhance the efficiency of the DSSCs based on such systems.

Efficient D-π-π-A-Type Dye Sensitizer Based on a Benzothiadiazole Moiety: A Computational Study

“…There is a large body of literature on (TD)DFT studies of D-π-A systems, even if one only focusses on those systems with a cyanoacrylic-acid acceptor (e.g., [ 8 , 9 , 10 , 12 , 14 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]). Most of these studies lack experimental verification and, therefore, should be viewed as an in silico screening of potential sensitizer materials.…”

Mapping the Progress in Natural Dye‐Sensitized Solar Cells: Materials, Parameters and Durability

“…Ruthenium (Ru) is a notable synthetic dye with good stability and excellent redox properties, responsive to pure visible light [278] and can dramatically improve efficiency by 10–11 % according to researchers. But Ru has limited resources and the price is extremely high [279,280] . Copper and zinc porphyrins have recently been considered an alternative to Ru due to their high price [281] .…”

“…But Ru has limited resources and the price is extremely high. [279,280] Copper and zinc porphyrins have recently been considered an alternative to Ru due to their high price. [281] N3, N719, N749 and Z907 are the renowned Ru complexes used for DSSC.…”

Enhancing the photoresponse by CdSe‐Dye‐TiO2‐based multijunction systems for efficient dye‐sensitized solar cells: A theoretical outlook

“…The time‐dependent density functional theory was used for the excited state studies by employing the CAM‐B3LYP functional. The CAM‐B3LYP has been found to provide good results for carrying out TDDFT studies involving charge transfers by many researchers . UV–visible studies were carried out in acetonitrile (AN) taking into account the 10 lowest spin allowed singlet‐to‐singlet transitions.…”

“…The sensitizer is a key component of a DSSC and is essential for efficient power conversion . The organic DSSCs are, however, better in comparison with the inorganic sensitizers, although they are more efficient, due to their easy availability and flexibility …”