Ionic benzo[α]phenoxazines as photosensors through DSSC device fabrication

Application of dye-sensitized solar cell (DSSC) fabrication technique is the most straightforward protocol for constructing photosensors cost-effectively and eco-friendly. However, despite having all the prerequisites for effective photo-sensing activity, benzo[α]phenoxazines have not yet been explored in the photosensors industry. In this context, three charged benzo[α]phenoxazine photosensitizers are implemented as effective photosensors through the DSSC device fabrication technique. The sodium salt of 6,10-dimethyl-5-methylene-5H-benzphenoxazin-5-one (MB-1) and 6-methyl-5-methylene-5H benzo[α]phenoxazin-5-one (MB-2) along with the sodium salt of 6-methyl-5-methylene-5H-benzo[α]phenothiazin-5-one (MB-3) were strategically employed due to it’s significant planar shape, double bond extended conjugation, well-positioned Highest Occupied Molecular Orbital (HOMO), Lowest Unoccupied Molecular Orbital (LUMO) levels, and ionic character which facilitate excellent electron transfer in the device. The dyes showed modified photo-sensing activity regarding sensitivity, photoresponsivity, specific detectivity, and significant quantum efficiency within the solar spectrum range. Among the resulting devices, MB-2 possesses the highest photoresponsivity of 1.81 × 10 −3 A/W and photodetectivity of 36.9 × 10 6 Jones. The device containing MB-2 dye efficiently detects the photo signals with the fastest speed at 352 ms and 165.38% sensitivity. The synergic impact of current density ( J sc ), open-circuit voltage ( V oc ), recombination resistance ( R REC ), and high charge collection efficiency ( η cc ) of 99.6% with an average electron lifetime of 57.19 ms develop high photo-sensing ability in MB-2 dye. Additionally, anatase TiO 2 with Ti +4 oxidation state confirmed from XPS and Raman spectra enhances the photo-sensing activity. Furthermore, the stability and reliability of the devices in terms of relative balance were 97.7–99.4% towards photo-sensing activity with DSSC device fabrication in the field of photosensors.