Triazine-Bridged Porphyrin Triad as Electron Donor for Solution-Processed Bulk Hetero-Junction Organic Solar Cells

Abstract

In this report we describe the use of a novel porphyrin triad (PPT) consisting of two zinc-metalated porphyrin units and one free-base porphyrin unit covalently linked through their peripheral amino-phenyl groups to a central s-triazine unit, in combination with PC 70 BM ([6,6]-phenyl C 70 butyric acid methyl ester), as electron donor and electron acceptors, respectively, for the fabrication of small-molecule based, solution-processed, bulk heterojunction (BHJ) organic solar cells. Photoluminescence studies of PPT:PC 70 BM blend films indicated that charge transfer is possible from PPT to PC 70 BM molecules. The solutionprocessed BHJ organic solar cell with the PPT:PC 70 BM blend in 1:1 weight ratio, processed from THF, was found to exhibit an overall power conversion efficiency (PCE) of 2.85%. When the BHJ active layer of PPT:PC 70 BM was processed from a 5% v/v mixture of 1-chloronaphathalene (CN) in THF, the PCE of the solar cell was increased up to 3.93%. This was attributed to the enhancement of the short circuit current J sc of the solar cell, which was ascribed to a stronger and broader incident photon to current efficiency (IPCE) response and to the higher degree of crystallinity of the active layer of the latter solar cell. The different surface morphologies of the two differently processed active layers result in different electron transport kinetics, and, as shown by electrochemical impedance spectra (EIS) and relaxation time measurements, the device with the active layer with the higher degree of crystallinity results in faster charge transfer process and more efficient exciton dissociation at the PPT/PC 70 BM interface.

CuSCN as selective contact in solution-processed small-molecule organic solar cells leads to over 7% efficient porphyrin-based device

“…8a was obtained as a green-red solid (0.06mmol, 115mg, 95.5 % yield), mp: >300°C. 1 H-NMR (400 MHz, CDCl 3 ) δ/ppm: 9.09 (d,4H,J = 3.9 Hz),30.87,30.80,30.75,30.58,26.42,26.29,26.22,26.09,26.02,25.99,25.89,25.80,25.69,25.60,25.49,25.38,24.33,24.21,24.11,15.22,15.20,15.16,15.14,15.04,13. 2930,2860,1700,1570,1490,1460,1400,1320,1240,1190,1140,1070,957,850,789,708.…”

Efficient co-sensitization of dye-sensitized solar cells by novel porphyrin/triazine dye and tertiary aryl-amine organic dye

“…A shown in Scheme 2, the synthesis of ZnP-triazine-(gly) 2 starts from cyanuric chloride, a reagent that has been widely used as template for the construction of a variety of multi-component molecular assemblies [18,[27][28][29][30]. The reactivity of cyanuric chloride is based on the temperature-dependent, stepwise nucleophilic substitution of its three chlorine atoms that allows the sequential introduction of different nucleophiles and leads to the synthesis of symmetrical and unsymmetrical assemblies, through simple, one-pot, and high-yield reaction procedures.…”

“…Our research group has utilized triazine as scaffold for the construction of porphyrin dyads and triads yielding DSSCs with moderate PCE values [16]. Triazine-bridged porphyrin arrays have been also incorporated by Luechai et al [17] and recently by us [18] as electron donors in bulk heterojunction solar cells.…”

A triazine di(carboxy)porphyrin dyad versus a triazine di(carboxy)porphyrin triad for sensitizers in DSSCs

“…They offer the great advantage of adjusting the electronic levels of their macrocycle by simply changing the porphyrin substituents − 3 at the meso and β-positions, or by changing the complexed metal, with Zn II proving to be the best choice for obtaining efficient sensitizers. 19 Moreover, our group has recently developed a synthetic approach towards oligomeric porphyrinic derivatives with carboxylic acid anchoring groups. 7 Recently, Grätzel's research group sensitized a DSSC using a modified porphyrin dye SM315.…”