Donor−Acceptor‐Functionalized Subphthalocyanines for Dye‐Sensitized Solar Cells

Abstract

Boron subphthalocyanines (SubPcs) are attractive as light harvesting materials in photovoltaic devices. Here we present the synthesis, optical and electrochemical properties, and device performances of a series of donor−acceptor‐functionalized SubPc derivatives incorporating a carboxylic acid for anchoring onto TiO2. Liquid‐ and solid‐state dye‐sensitized solar cells (DSCs) were prepared from three compounds, and a triad system consisting of two aniline donor moieties and a benzothiadiazole acceptor moiety was found to exhibit the highest power conversion efficiency (PCE) in the series (PCE=1.54 %; solid‐state device). The compounds were prepared by stepwise acetylenic coupling reactions. In addition, we present the synthesis and optical properties of a SubPc derivative incorporating three anilino‐substituted 1,1,4,4‐tetracyanobutadiene units, prepared by the [2+2] cycloaddition between three ethynyl units at the SubPc periphery and three tetracyanoethylene molecules followed by electrocyclic ring‐opening reactions.

Charge‐Transfer in Panchromatic Porphyrin‐Tetracyanobuta‐1,3‐Diene‐Donor Conjugates: Switching the Role of Porphyrin in the Charge Separation Process

“…Importantly, in the near-IR region covering the 650-900 nm range, a new broad absorption band was observed in all TCBD bearing systems as a consequence of intramolecular charge transfer involving the electron deficient TCBD and the electron rich porphyrin and second donor entities. [33][34][35][36][37][38][39][40][41][42][43] In summary, intramolecular charge transfer in the ground state was successfully established in these MP-TCBD-Donor (M = 2H or Zn; donor = PTZ or NND) conjugates.…”

“…TCBD is a cyano-rich moiety [25] that has been covalently linked to many electroactive units including porphyrins, phthalocyanines and BODIPYs. [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] In most of these TCBD-based D-A conjugates, photoinduced charge separation has been observed as a consequence of coupling between the electron-poor TCBD and electron-rich sensitizer. In the literature reported porphyrin-TCBD systems, [41][42] porphyrin was function-alized at the meso-position with a TCBD entity either directly or with a phenyl ring spacer.…”

Charge stabilization via electron exchange: excited charge separation in symmetric, central triphenylamine derived, dimethylaminophenyl–tetracyanobutadiene donor–acceptor conjugates

“…[42][43][44][45][46][47][48] The photochemical behavior of a few donor-TCBD derived systems have been reported in the literature. [49][50][51][52][53][54][55][56] Although with high quantum yields, due to close proximity between the donor and acceptor entities, ultrafast charge separation and recombination was observed in these systems. That is, no charge stabilization could be accomplished.…”

Subphthalocyanine–tetracyanobuta-1,3-diene–aniline conjugates: stereoisomerism and photophysical properties

“…Recently, 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) has been investigated as novel molecular partner for SubPcs. [11][12][13] Up to now, few TCBD-based D-A arrays have been reported, in which the TCBD moiety, a strong electron-withdrawing group, has been linked to electroactive units such as anilines, 14 porphyrins, 15 corannulenes, 16 or phthalocyanines. 17 In most of these systems, photoinduced energy and/or electron transfer has been observed.…”