Synthesis and characterization of novel thieno[3,2- b ]thiophene based metal-free organic dyes with different heteroaromatic donor moieties as sensitizers for dye-sensitized solar cells

Abstract

Four novel heterocycle dyes 3a-d were synthesized in order to study the variations produced in the optical, electronic and photovoltaic properties by substitution of different electron-rich heterocyclic groups to the thieno[3,2-b]thiophene system. The final push-pull conjugated dyes 3a-d were synthesized by Suzuki-Miyaura coupling reaction followed by Knoevenagel condensation of the corresponding aldehyde precursors with cyanoacrylic acid 2a-d. These new push-pull systems are based on a thieno[3,2-b]thiophene spacer, a cyanoacetic acid anchoring group and several electron-rich heterocycles (thiophene, pyrrole and furan) as donor groups. The multidisciplinary study concerning the optical, redox and photovoltaic characterization of the dyes reveals that compound 3b bearing a hexyl-bithiophene donor group/heterocyclic spacer exhibits the best overall conversion efficiency (2.49%) as sensitizer in nanocrystalline TiO 2 dye sensitized solar cells. Co-adsorption studies between N719 and 3b revealed that upon addition of N719 co-adsorbent, the optimized cell efficiencies were improved by 16e77%. The best efficiency was 4.40%, corresponding to 54% of the photovoltaic performance of the N719-based DSSC fabricated and measured under similar conditions.

Optical and Photovoltaic Properties of Thieno[3,2-b]thiophene-Based Push–Pull Organic Dyes with Different Anchoring Groups for Dye-Sensitized Solar Cells

“… b E HOMO = −(4.39 + E ox ) (eV) and E LUMO = −( E red + 4.39) (eV). 59 , 60 c Calculated from the difference between the onset potentials for oxidation and reduction. …”

“…CV was performed using an AUTOLAB electrochemical station in a three-electrode cell configuration, as elsewhere reported, 59 and measured at a scan rate of 0.1 V s –1 (see Figure S13 ). The solutions were deoxygenated by bubbling nitrogen before each measurement.…”

Small Heterocyclic D‐π‐D‐π‐A Push‐Pull Molecules with Complex Electron Donors

“…On the other hand, recent theoretical and experimental studies showed that proper involvement of thiophene, pyrrole, and furan rings in the chromophore backbone may bring organic materials with advanced properties. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Despite their popularity as auxiliary donors, [32] a combination of five-membered heterocyclic and mesomeric donors has been practically realized only on thiophene. [33][34][35] Pyrrole or furan π-linkers with appended alkoxy or amino mesomeric donors are scarce.…”

Heterocyclic Aldehydes Based on Thieno[3,2-b]thiophene Core: Synthesis and Preliminary Studies as Ion Optical Chemosensors

“…An electrophilic aromatic substitution of the substrate takes place, followed by hydrolysis to yield the heterocyclic carbaldehyde [3]. -Conjugated heterocyclic aldehydes can also be prepared through Suzuki cross coupling reaction using the appropriate coupling components [6][7][8][9].…”