Push-pull phenoxazine-based sensitizers for p-type DSSCs: Effect of acceptor units on photovoltaic performance
Résumé
Finding new efficient p-type sensitizers for NiO photocathodes is a great challenge for the development of promising low-cost tandem DSSCs. Now, the focus of researchers investigating these cells has been to create high-performance p-type systems. With this intention, herein, we report the design and synthesis of six new phenoxazine-based D-A configured organic dyes PO1-6 comprising different acceptor moieties specially designed for the sensitization of mesoporous p-type semiconductor NiO for the construction of p-type dyesensitized solar cells (p-DSSCs). This work includes structural, photophysical, thermal, electrochemical, theoretical, and photoelectrochemical studies of these dyes, including evaluation of their structure-property relationships. The optical studies revealed that PO1-6 display adequate absorption and emission features in the range of 480-550 nm and 560-650 nm, respectively, with a bandgap in the order of 2.05-2.40 eV, and their thermodynamic parameters favour an efficient interfacial charge transfer involving NiO. Among the six new dyes, the device based on sensitizer PO2 carrying electron-withdrawing 1,3-diethyl-2thiobarbituric acid achieved the highest PCE of 0.031 % (JSC: 0.89 mA⸳cm-2 , VOC: 101 mV, and FF: 35 %). Conclusively, the study furnishes an understanding of the intricacies involved in the structural modification of phenoxazine-based sensitizers to further ameliorate the performance of the p-type DSSCs.
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