Self‐Power Organic Photosensor for DSSCs Applications: 2‐((2‐hydroxy‐5‐nitrophenyl)amino)naphthalene‐1,4‐dione as a Model Example

Abstract The anilino‐substituted 1,4‐naphthoquinone‐based photosensitizer, namely, 2‐((2‐hydroxy‐5‐nitrophenyl)amino)naphthalene‐1,4‐dione (LwNAP), has been synthesized and characterized. The presence of both the hydroxy group and the electron‐withdhrawing nitro group in the LwNAP ligand facilitates efficient charge separation within its donor‐ π‐ acceptor (D‐ π‐ A) structure, making it a promising candidate for a self‐powered organic photosensor in dye‐sensitized solar cells (DSSCs). X‐ray diffraction analysis reveals that LwNAP crystallizes in the monoclinic P2 1 /n space group. The extended conjugation of the naphthoquinone moiety results in broad visible‐spectrum absorption, suggesting that LwNAP can be explored for efficient sunlight harvesting. The UV‐visible experiments have shown that the complex formation of LwNAP with TiO 2 and ZnO photoanodes results in redshifted bands at 521 and 543 nm, respectively, due to interactions with the photoanodes. Furthermore, the UV‐visible and fluorescence spectral measurements suggested an energy band gap of 2.60 eV for LwNAP. At the same time, the electrochemical analysis indicated that the LUMO was located at ‐3.79 eV, aligning well with the conduction bands of TiO 2 and ZnO, facilitating effective electron injection. A comparison of TiO 2 /LwNAP and ZnO/LwNAP photoanodes indicates superior photovoltaic performance for the TiO 2 /LwNAP system. Moreover, the chronoamperometry experiments demonstrated that TiO 2 /LwNAP exhibits exceptional photoresponsivity (7.08 × 10 −3 A/W), photodetectivity (11.62 × 10 6 Jones), combined with a rapid response time (1867 ms), high sensitivity (60104%), and an effective quantum efficiency at 400 nm (2.199%). These findings suggest that TiO 2 /LwNAP is a promising candidate for sensitized photoanodes and can be explored in advanced photovoltaic and photo‐sensing applications.