Influence of Phenylethynylene of Push–Pull Zinc Porphyrins on the Photovoltaic Performance

Abstract

A series of zinc porphyrin dyes YD22-YD28 were synthesized and used for dye-sensitized solar cells. Dyes YD26-YD28 consist of zinc porphyrin (ZnP) as core unit, arylamine (Am) as electron-donating group, and p-ethynylbenzoic acid (EBA) as an electron-withdrawing/-anchoring group. The dyes YD22-YD25 contain additional phenylethynylene group (PE) bridged between Am and ZnP units. The influence of the PE unit on molecular properties as well as photovoltaic performances were investigated via photophysical and electrochemical studies and density functional calculations. With the insertion of PE unit, the dyes YD22-YD25 possess better light-harvesting properties in terms of significantly red-shifted Q-band absorption. The conversion efficiencies for dyes YD22-YD25 are better than those of dyes YD26-YD28 owing to larger J(SC) output. Natural transition orbitals and Mulliken charge analysis were used to analyze the electron injection efficiency for porphyrin dyes upon time-dependent DFT calculations. The results indicated that insertion of additional PE unit is beneficial to higher J(SC) by means of improved light-harvesting property due to broadened and red-shifted absorption.

Evolution of Molecular Design of Porphyrin Chromophores for Photovoltaic Materials of Superior Light‐to‐Electricity Conversion Efficiency

“…Molecules with bulky alkyl peripheral groups occupy more space on the MO surface, thereby decreasing light absorbance. Despite the substantially lower surface concentration, these molecules however, advantageously increase the PCE of the DSSC by 1.5% compared to that with the same dye but not terminated with alkyl chains (Scheme ) . A similar trend was reported elsewhere (Table ) …”

“…Comparison of the auxiliary donor group termination influence on the power conversion efficiency of DSSC …”

“…Because of parasitic processes, including recombination of electrons injected into the CB of TiO 2 and reduction of the charge mediating species with electrons from the photoexcited dye, the difference between differently connected auxiliary donors is not well‐distinguished . However, an improved molecular design of YD25 and YD26 (Scheme ) allows partial hampering of these processes and determining certain superiority of the amine over ethynyl linking of the 20‐ meso substituent, despite ∼15% lower surface concentration of the YD26 dye (Table ) …”

Push-Pull Zinc Porphyrins as Light-Harvesters for Efficient Dye-Sensitized Solar Cells

“…Porphyrins constructed with dialkylaminophenyl groups always show broader light-harvesting area than the diarylamino ones, even the latter possess larger conjugation area. LD14 porphyrin (Figure S1 ) features with 4-ethynyl-N,N-dimethylaniline as donor group while the acceptor is similar to YD2 (Chou et al, 2016 ). This porphyrin showed a wide IPCE onset till to 780 nm because of a Q band maximum at 667 nm, impressive high PCE of 10.2% was obtained.…”

Effect of long alkyl chains of aniline donor on the photovoltaic performance of D‐π‐A zinc porphyrin for dye‐sensitized solar cells

“…In 2016, we reported a series of porphyrin‐based sensitizers, YD22‐YD28 , and YD24 , among which the porphyrin dye featuring a triarylaminophenylethynyl with long carbon alkyl groups achieved a PCE of 9.19%. The introduction of long carbon alkyl groups into triarylamine functional groups significantly reduces molecular aggregation and contributes to the improved PCE . Here, we developed and synthesized three zinc porphyrin dyes, JJ1 , JJ2 , and JJ6 .…”