Syntheses of organic dyes based on phenothiazine as photosensitizers and effects of their π-conjugated bridges on the photovoltaic performances of dye-sensitized solar cells

Three organic dyes, 2-cyano-3-(N-hexylphenothiazine-3-yl)acrylic acid (H-PTZ), 2-cyano-3-(5′-(2-(Nhexylphenothiazine-3-yl)vinyl)-2,2′-bithiophen-5-yl)acrylic acid (H-PTZ-BT), and 2-cyano-3-(5-(4-((4-(2-(N-hexylphenothiazine-3-yl)vinyl)phenyl)(phenyl)amino)phenyl)thiophen-2-yl)acrylic acid (H-PTZ-TPA-T), based on the phenothiazine (PTZ) unit as an electron donor moiety and cyanoacrylic acid unit as an electron acceptor moiety were synthesized to study the effect of a π-conjugated bridge of the dye on the performance of the resulting dye-sensitized solar cells devices. The thiophene unit and triphenylamine were introduced as a π-conjugated bridge. The H-PTZTPA-T-sensitized cell showed the highest overall conversion efficiency of 4.01% (Jsc: 9.64 mA·cm−2; Voc: 0.69 V; FF: 0.60), while the H-PTZ-sensitized cell showed the lowest value of 3.57% (Jsc: 7.76 mA·cm−2; Voc: 0.70 V; FF: 0.65) among the cells based on the three organic dyes compared to 5.09% for the cell based on the N719 dye (Jsc: 12.77 mA·cm−2; Voc: 0.72 V; FF: 0.55) under AM 1.5 illumination (100 mW·cm−2). Open image in new window