Asymmetric zinc phthalocyanines with large steric hindrance as efficient red/near-IR responsive sensitizer for dye-sensitized solar cells

Effect of carboxyl anchoring groups in asymmetric zinc phthalocyanine with large steric hindrance on the dye-sensitized solar cell performance

“…Zn-tri-PcNc-4/Zn-tri-PcNc-8 were prepared via a mixed cyclic tetramerization by using 6:1 of 4,5-bis([1,1 0 :3 0 ,1 00 -terphenyl]-2'-yloxy) phthalonitrile and 1,3-dioxo-2-phenyl-2,3-dihydro-1H-benzo[f] isoindole-6,7-dicarbonitrile /6-carboxymethyl-2,3-dicyano-naphthalene followed by ester hydrolysis with Na and methanol similar to the previous report [13]. The obtained asymmetric ZnPcs and their corresponding intermediates were fully characterized by elemental analysis and spectroscopic techniques, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), 1 H NMR, IR, UVevis and fluorescence spectroscopy in our previous literatures [16,17]. For example, Zn-tri-PcNc-4 (Yield: 98 mg, 98%.…”

“…Both of the two ZnPc derivatives exhibited two one-electron oxidation and up to three one-electron reduction processes within the electrochemical window of DCB [16,17]. The limited differences between the corresponding reduction/oxidation potentials of both ZnPcs imply their reversible or quasireversible redox nature, which can be attributed to successive removal/addition of one electron from/to the Pc ring-based orbitals [13,16,17]. The corresponding first redox potentials (named as E ox and E red , respectively) of the two ZnPc derivatives are listed in Table 1.…”

“…Electrochemical properties of Zn-tri-PcNc-4 and Zn-tri-PcNc-8 were also scrutinized by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) as reported in our previous publications [16,17]. Both of the two ZnPc derivatives exhibited two one-electron oxidation and up to three one-electron reduction processes within the electrochemical window of DCB [16,17].…”

“…The optical energy gaps (E 0-0 ) of ZnPcs can be calculated by using their absorption and emission spectra [19e21]. Zn-tri-PcNc-4/Zn-tri-PcNc-8 have the maximum emissions at 739/718 nm as shown in their fluorescence spectra reported in our previous publications [16,17], and the corresponding calculated E 0-0 values of Zn-tri-PcNc-4/Zn-tri-PcNc-8 are 1.72/ 1.75 eV as shown in Table 1.…”

“…Their synthetic pathways, experimental procedures and characterizations on composition, structure and property were reported elsewhere [16,17]. Experimental results indicate that Zntri-PcNc-4 bearing two carboxyl groups shows a slight Q-band redshift in the red/near-IR region but a significantly decreased absorbance as compared with Zn-tri-PcNc-8 bearing one carboxyl group, and the solar cell sensitized with Zn-tri-PcNc-4 yielded a 3.22% efficiency, higher than that (3.01%) of the solar cell sensitized with the analog (Zn-tri-PcNc-8) with one carboxyl group.…”