Ethynyl Linker Research Articles

Non-fused ring electron acceptors with an ethynylene linker for non-halogenated solvent-processed organic solar cells

This study explores the design, synthesis and application of two non-fused ring electron acceptors (NFREAs), namely PAcT-Cl and CAcT-Cl, featuring an ethynylene linker, in non-halogenated solvent-processed organic solar cells (OSCs).

Effect of the charge-separated state on the 3MLCT state: Synthesis and study of the photophysics of electron donor-acceptor dyads based on Pt(II)-Schiff base coordination framework and naphthalenediimide chromophore

We prepared Pt(II)-Salen Schiff base complexes with a naphthalenediimide (NDI) unit attached on the coordination framework, to study the intersystem crossing (ISC), the charge separation, and the possible formation of a long-lived triplet charge separated (CS) state. The Pt(II)-Schiff base coordination framework acts as electron donor and it shows ultrafast ISC (<1 ps) and small Stokes shift. NDI acts as electron acceptor. The two units are attached either via a phenyl linker (Pt-NDI) or phenyl ethynyl linker (Pt-CC-NDI). Negligible electronic interaction between the Pt(II)-Schiff base coordination framework and the NDI unit at ground state was observed for both dyads, whereas the phosphorescence of the Pt(II)-Schiff base coordinated framework was quenched to large extent in the dyads, as compared to the reference complexes containing no NDI unit, especially in polar solvents. Electrochemical and optical spectral data show that the CS state energy is 1.93 eV, 1.82 eV, 1.54 eV, 1.43 eV in n-hexane (HEX), toluene (TOL), tetrahydrofuran (THF), acetonitrile (ACN), respectively. In comparison, the 3MLCT state and 3NDI state energy are 1.97 and 2.04 eV, respectively. Nanosecond transient absorption spectra show the formation of the 3MLCT state for Pt-CC-NDI, whose lifetimes is shortened in polar solvents (τT = 3.5 µs, 2.1 µs, 22 ns, and 19 ns in HEX, TOL, THF and ACN, respectively), similar trend was observed for Pt-NDI. Femtosecond transient absorption spectra show that the charge separation takes less than 1 ps both in toluene and acetonitrile. Quenching of the otherwise long-lived triplet excited state (3.5 µs) by a short lived CS state may be developed as a photo-protection mechanism similar to that found in natural photosynthetic apparatus.

Computational prediction of the properties of bis(ethynylthienyl)dialcoxynaphthalene‐based conjugated polymers for organic solar cell applications

AbstractA series of homo‐ (P0) and copolymers (P1‐P5) based on the electron‐donor building‐block 2,2′‐(2,3‐bis(2‐ethylhexyloxy)naphthalene‐1,4‐diyl)bis(ethyne‐2,1‐diyl)dithiophene (1,4‐NET) including ethynyl linkers aiming to promote coplanarity were designed, and their properties predicted using theoretical methodologies to evaluate their potential in organic solar cell applications. The geometries, FMO levels, energy bandgaps, and absorption spectra of trimer models were determined using time‐dependent density functional theory, while their photovoltaic and charge‐transport properties were estimated by the Scharber's model and semiclassical Marcus theory, respectively. Compared to high‐performance conjugated polymers (CPs), such as PTB7‐Th or PM6, and similar systems based on the 1D‐BDT unit, the HOMO and LUMO levels of P0‐P5 tend to be higher. In addition, the new CPs have complementary absorptions with narrow‐bandgap acceptors, such as ITIC and Y6, and adequate matches between their HOMO and LUMO levels. Although the simulated photovoltaic and charge‐transport properties could be overestimated, the best candidate to be synthesized and tested in organic solar cells is P5 due to its suitable and well‐balanced properties, demonstrating the positive effect of incorporating ethynyl bridges to improve the optoelectronic properties of CPs.

One‐Photon and Two‐Photon Absorption Properties of Multi‐Branched Squaraine Dyes Comprised of Triphenylamine Cores and Ethynylene Linkers

AbstractWe developed multi‐branched π‐conjugated systems using squaraine dyes with triphenylamine cores connected by ethynylene linkers. We investigated the influence of interbranch coupling between squaraine branches on their one‐photon (OPA) and two‐photon absorption (TPA) properties. These dyes with triphenylamine components showed a red‐shifted one‐photon absorption (OPA) compared to the precursor squaraine dyes. Among branched dyes, the lack of apparent splitting or shift in the absorption maxima, even as the absorption intensity increased with the number of chromophores, implies the presence of limited exciton coupling between the squaraine branches. The present squaraine dyes with triphenylamine cores exhibited a moderate TPA compared to the precursor squaraine without the triphenylamine core, due to the extended π‐conjugation. Notably, both the 3‐branched and 2‐branched dyes demonstrated additional enhancement in the TPA response, surpassing that of the monochromophoric counterpart. This resulted in achieving a substantial TPA cross section of up to 3905 GM at 830 nm.

Antiviral activity of singlet oxygen-photogenerating perylene compounds against SARS-CoV-2: Interaction with the viral envelope and photodynamic virion inactivation

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has prompted great interest in novel broad-spectrum antivirals, including perylene-related compounds. In the present study, we performed a structure–activity relationship analysis of a series of perylene derivatives, which comprised a large planar perylene residue, and structurally divergent polar groups connected to the perylene core by a rigid ethynyl or thiophene linker. Most of the tested compounds did not exhibit significant cytotoxicity towards multiple cell types susceptible to SARS-CoV-2 infection, and did not change the expressions of cellular stress-related genes under normal light conditions. These compounds showed nanomolar or sub-micromolar dose-dependent anti-SARS-CoV-2 activity, and also suppressed the in vitro replication of feline coronavirus (FCoV), also termed feline infectious peritonitis virus (FIPV). Perylene compounds exhibited high affinity for liposomal and cellular membranes, and efficiently intercalated into the envelopes of SARS-CoV-2 virions, thereby blocking the viral–cell fusion machinery. Furthermore, the studied compounds were demonstrated to be potent photosensitizers, generating reactive oxygen species (ROS), and their anti-SARS-CoV-2 activities were considerably enhanced after irradiation with blue light. Our results indicated that photosensitization is the major mechanism underlying the anti-SARS-CoV-2 activity of perylene derivatives, with these compounds completely losing their antiviral potency under red light. Overall, perylene-based compounds are broad-spectrum antivirals against multiple enveloped viruses, with antiviral action based on light-induced photochemical damage (ROS-mediated, likely singlet oxygen-mediated), causing impairment of viral membrane rheology.

Structure-guided optimization of adenosine mimetics as selective and potent inhibitors of coronavirus nsp14 N7-methyltransferases

The COVID-19 pandemic reveals the urgent need to develop new therapeutics targeting the SARS-CoV-2 replication machinery. The first antiviral drugs were nucleoside analogues targeting RdRp and protease inhibitors active on nsp5 Mpro. In addition to these common antiviral targets, SARS-CoV-2 codes for the highly conserved protein nsp14 harbouring N7-methyltransferase (MTase) activity. Nsp14 is involved in cap N7-methylation of viral RNA and its inhibition impairs viral RNA translation and immune evasion, making it an attractive new antiviral target. In this work, we followed a structure-guided drug design approach to design bisubstrates mimicking the S-adenosylmethionine methyl donor and RNA cap. We developed adenosine mimetics with an N-arylsulfonamide moiety in the 5′-position, recently described as a guanine mimicking the cap structure in a potent adenosine-derived nsp14 inhibitor. Here, the adenine moiety was replaced by hypoxanthine, N6-methyladenine, or C7-substituted 7-deaza-adenine. 26 novel adenosine mimetics were synthesized, one of which selectively inhibits nsp14 N7-MTase activity with a subnanomolar IC50 (and seven with a single-digit nanomolar IC50). In the most potent inhibitors, adenine was replaced by two different 7-deaza-adenines bearing either a phenyl or a 3-quinoline group at the C7-position via an ethynyl linker. These more complex compounds are barely active on the cognate human N7-MTase and docking experiments reveal that their selectivity of inhibition might result from the positioning of their C7 substitution in a SAM entry tunnel present in the nsp14 structure and absent in the hN7-MTase. These compounds show moderate antiviral activity against SARS-CoV-2 replication in cell culture, suggesting delivery or stability issue.

A facile approach to create sensitive and selective Cu(ii) sensors on carbon fiber microelectrodes.

A facile platform derived from deposition of ethynyl linkers on carbon fiber microelectrodes has been developed for sensitive and selective sensing of Cu(ii). This study is the first to demonstrate the successful anodic deposition of ethynyl linkers, specifically 1,4-diethynylbenzene, onto carbon fiber microelectrodes. Multi-scan deposition of DEB on these microelectrodes resulted in an increased sensitivity and selectivity towards Cu(ii) that persists amidst other divalent interferents and displays sustained performance over four days while stored at room temperature. This method can be extended to other ethynyl terminal moieties, thereby creating a versatile chemical platform that will enable improved sensitivity and selectivity for a new frontier of biomarker measurement.

Corralarenes: A Family of Conjugated Tubular Hosts.

Despite the advances in host-guest chemistry, macrocyclic hosts with deep cavities are far from abundant among the large number of wholly synthetic hosts described in the literature. Herein, we describe the design and synthesis of two new tubular hosts, namely, corral[4]arene and corral[5]arene. The former has been isolated and characterized as two conformational diastereoisomers, one is centrosymmetric and the other asymmetric. The latter, a fivefold symmetrical and flexible host, has also been investigated in detail. It is composed of five 4,4'-dimethoxybiphenyl units bridged by ethynylene linkers at their 2,2'-positions and adopts a pentagonal conformation with a tubular-shaped cavity in the presence of guests. This structure endows corral[5]arene not only with a conjugated backbone, capable of bright fluorescent emission (quantum yield, 56%), but also a deep π-electron-rich aromatic cavity with remarkable conformational flexibility. The adaptive cavity of corral[5]arene allows it to accommodate a wide range of neutral and positively charged electron-deficient guests with different molecular sizes and shapes. Binding constants between this host and these guests in three different nonpolar organic solvents lie in the range of 103 to 107 M-1. Moreover, corral[5]arene exhibits dynamic chirality on account of the axes of chirality associated with each of the five biphenyl units and displays first-order transformation as exhibited by circular dichroism in response to the addition of chiral guests. All these stereochemical features render corral[5]arene an attractive host for a variety of supramolecular and nanotechnological applications.

Influence of twisted or planar linkers on the performance of quasi-two-dimensional fused perylene diimide acceptors for organic solar cells

Quasi-two-dimensional (quasi-2D) fused perylene diimide building block is effective for constructing high-performance non-fullerene acceptors, while the exploration of their structure-property relationship remains critical, yet challenging. Herein, two quasi-2D non-fullerene acceptors (FPDI-V and FPDI-E) featuring vinylene or ethynylene linker were developed to reveal the effects of molecular geometry on photophysics, morphology and device performances. We observed that such minor chemical variations can lead to distinct difference on absorption spectra, energy levels, and the photovoltaic properties, but only have slight effects on crystallinity, molecular packing and film morphology. The resulting device based on PTB7-Th:FPDI-V delivered a power conversion efficiency of 7.53%, which is higher than those of FPDI-E based device (6.37%). The improved photovoltaic performance of FPDI-V with a twisted vinylene linker should come from the enhanced absorption coefficient, upshifted molecular energy levels, higher exciton dissociation rate, and weaker charge recombination. This result provides an updated idea for further designing and structural optimizing of quasi-2D non-fullerene acceptors.

Chiral π-Conjugated Liquid Crystals: Impacts of Ethynyl Linker and Bilateral Symmetry on the Molecular Packing and Functions

Recently, various chiral aromatic compounds, including chiral π-conjugated liquid crystals, have been developed for their unique photofunctions. One of the typical photofunctions is the bulk photovoltaic effect of ferroelectric π-conjugated liquid crystals, which integrates a polar environment based on molecular chirality with an extended π-conjugation system. Tuning the spectral properties and molecular packing is essential for improving the optical functions of the chiral π-conjugated liquid crystals. Herein, we examined the effects of an ethynyl linker and bilateral symmetry on the liquid-crystalline (LC) properties and π-conjugated system through detailed characterization via polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction analysis. The spreading of the π-conjugated system was evaluated using UV–vis absorption and photoluminescence spectroscopy. Bilateral symmetry affects the LC and photoluminescent properties. Hetero-substitution with a sparse ethynyl linker likely allows the formation of an interdigitated smectic LC structure. Because the molecular packing and photophysical properties can affect the photo- and electrical functions, we believe this study can promote the molecular design of novel functional π-conjugated materials, such as chiral ferroelectric π-conjugated liquid crystals, exhibiting the bulk photovoltaic effect.

Platinum octaethylporphyrin-diphenylanthracene dyad with an ethynylene linker

A platinum octaethylporphyrin (PtOEP)-diphenylanthracene (DPA) dyad with an ethynylene linker was synthesized. PtOEP and DPA were used as a triplet sensitizer/energy donor and energy acceptor, respectively. UV–vis spectra suggested significant electronic coupling between PtOEP and the ethynylene linker in the ground state. Compared with the non-substituted PtOEP, emission from PtOEP in the dyad was almost completely quenched probably due to triplet excitation energy transfer from PtOEP to DPA.

Palladium(II) and Platinum(II) Porphyrin Donors for Organic Photovoltaics

Three new A-π-D-π-A structural porphyrin-based donors, C19-H2P, C19-PdP, and C19-PtP, are designed and synthesized, with porphyrin (D) moieties equipped with no metal, palladium (Pd), and platinum (Pt) as the core, respectively, and end-capped with electron-deficient 3-ethylrhodanine (A) via a π-bridge of phenylene ethynylene linker. C19-PdP and C19-PtP exhibit low-lying highest occupied molecular orbital levels than C19-H2P. The three porphyrin donors show highly intensified and broad absorptions at ca. 400–530 nm (Soret bands) and at ca. 550–800 nm (Q-bands) with an absorption valley at ca. 540 nm. Using PC71BM as an electron acceptor, the devices based on C19-PdP and C19-PtP donors achieve power conversion efficiencies (PCEs) of 8.09 and 7.31% under 1 Sun, respectively, whereas the C19-H2P device, that has no metal, has a very low PCE of 2.51%. Furthermore, at 300 lux LED source, the C19-PdP and C19-PtP devices deliver promising PCEs of 16.54 and 16.74%, respectively. The improved performance of C19-PdP- and C19-PtP-based devices is mainly due to more efficient charge collection, faster charge transport, more suppressed recombination behavior, and smoother surface morphology. These findings pave the way for the development of new metalloporphyrin-based donors for organic solar cells using simple structural engineering.

Bright Luminescence by Combining Chiral [2.2]Paracyclophane with a Boron-Nitrogen-Doped Polyaromatic Hydrocarbon Building Block.

Novel BN‐doped compounds based on chiral, tetrasubstituted [2.2]paracyclophane and NBN‐benzo[f,g]tetracene were synthesized by Sonogashira–Hagihara coupling. Conjugated ethynyl linkers allow electronic communication between the π‐electron systems through‐bond, whereas through‐space interactions are provided by strong π–π overlap between the pairs of NBN‐building blocks. Excellent optical and chiroptical properties in racemic and enantiopure conditions were measured, with molar absorption coefficients up to ϵ=2.04×105 M−1 cm−1, fluorescence quantum yields up to Φ PL=0.70, and intense, mirror‐image electronic circular dichroism and circularly polarized luminescence signals of the magnitude of 10−3 for the absorption and luminescence dissymmetry factors. Computed g lum,calcd. values match the experimental ones. Electroanalytical data show both oxidation and reduction of the ethynyl‐linked tetra‐NBN‐substituted paracyclophane, with an overlap of two redox processes for oxidation leading to a diradical dication.

Influence of π-Endcaps on the Performance of Functionalized Quinolines for p-Channel OFETs.

This study investigates the influence of aryl and ethynyl linkers as well the effect of various pi-end-groups on the performance of the quinoline-based organic field-effect transistors. A series of new functionalized quinolines with D-π-A-π-D and A-π-A-π-A architectures are designed and synthesized via the Sonagashira cross-coupling reaction. All the new compounds are well characterized and their photophysical properties are studied. The bottom gate-top contact-organic field-effect transistors devices are fabricated using the spin-coating technique. By employing the pre and post-annealing technique, films with uniform surface coverage are obtained. The variation in the end-groups results in versatile packing arrangements which determine their good charge transport properties. The p-channel transistor behavior is observed for all the new compounds. Among the molecules studied, methoxyphenyl and thiophen-2-yl terminal functionalized with D-π-A-π-D architecture exhibit the higher p-channel transistor characteristics with hole mobilities of 1.39 and 1.33 cm2 V-1 s-1 , respectively. The good charge carrier mobilities are supported by an electron-donating methoxy group and thiophene as the end-groups with high highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) levels, extensive π-conjugation, and better self-assembly.

Impact of ethynylene linkers on the optical and electrochemical properties of benzothiadiazole based alternate conjugated polymers

The effect of ethynylene spacers on the bandgap of alternating polymers, comprising 4,7-linked benzothiadiazole units and 2,7-linked fluorene, 2,7-linked carbazole or 2,6-linked anthracene repeat units has been investigated. The three novel polymers PFDEBT , PCDEBT and PPADEBT were prepared via the Sonogashira coupling reaction. The optical, electrochemical and thermal properties of the resulting polymers were compared and analysed. All polymers displayed low solubility in common organic solvents and have moderate molecular weights. Optical studies revealed that all the new ethynylene based-polymers displayed large bandgaps in excess of 2.1 eV. Results highlighted that incorporation of acetylene units between the benzothiadiazole electron accepting units and the other electron donor units over polymer chains leads to wide bandgaps as a result of the electron accepting properties of the acetylene units. The HOMO levels of the resulting polymers are unaffected by the different donor moieties used. However, varying the electron donor units can perturb the electron accepting ability of the main chain of polymers in this series and their LUMO levels. Anthracene-based polymer ( PPADEBT ) displayed the lowest LUMO level, while the fluorene-based polymer ( PFDEBT ) displayed the highest LUMO level. All polymers showed good stability to thermal degradation. The amorphous nature of these polymers was confirmed with powder X-ray diffraction studies.

Synthesis, photophysical properties and optical stabilities of dimethylthio modified dibenzosiloles: High quantum yield emitters

The straightforward synthesis of new rigid rod-like dimethylthio modified dibenzosiloles consisting of ethynylene linkages and different aryl end-groups is reported. The optical and electrochemical properties of the dimethylthio modified dibenzosilole compounds were investigated experimentally and computationally, revealing the photo-induced intramolecular charge transfer (ICT) and the resulting large Stokes shift for amino-substituted compounds. A series of dibenzosilole derivatives exhibit blue to green emissions with high fluorescence quantum yields up to 0.79 in solution and solid state. Except for the very high thermal stability attributed to the dibenzosilole core, the peripheral groups were found to play a key role for the optical stability. Deep insight into the mechanism demonstrates that the photooxidative degradation of methylthio units or the N, N‒dimethylamino group could be induced by the charge transfer complex (CTC) process, greatly impairing the photostability of the molecules. This discovery opens new design possibilities for extended dibenzosilole derivatives with prominent thermal and photo stability and emissions.

Preparation of Liquid Crystalline Subnaphthalocyanines As Optoelectronic Materials

Chloroboron(III) hexachloro- hexabromo-, and hexaiodosubnaphthalocyanines were prepared by cyclotrimerization of 6,7-dihalo-2,3-naphthalenedicarbonitrile in the presence of BCl3, They were converted to fluoroboron(III) hexahalosubnaphthalocyanine by the reaction with AgBF4. Their solubility, electronic absorption spectroscopy, fluorescence emission spectroscopy and HOMO/LUMO energy levels were evaluated. Fluorescence quantum yields of chloroboron(III) hexafluoro-, hexachloro-, hexabromo-, and hexaiodosubnaphthalocyanine were 0.22, 0.20, 0.11, 0.05, respectively, indicating that heavy atom effects of Br and I were effectively deactivate the singlet excited states. These subnaphthalocyanines showed lower HOMO/LUMO energies than the parent subnaphthalocyanine by 0.13 – 0.39 eV. The optical band gap decreased in the order: hexafluoro- > hexachloro- > unsubstituted > hexaiodo-subnaphthalocyanine. Hexaiodosubnaphthalocyanines were converted to chloroboron(III) and fluoroboron(III) hexa(1-alkynyl)- and hexa(2-arylethynyl)subnaphthalo-cyanines by Sonogashira coupling of hexaiodosubnaphthalocyanines with substituted acetylenes. Introduction of butyl or longer alkyl groups via ethynylene linkages on the periphery resulted in lower melting points, and higher solubility in dichloromethane. X-ray diffraction (XRD) patterns of the cast film indicated that hexa(2-(4-hexylphenyl)ethynyl)- and hexa(2-(4-hexyloxyphenyl)ethynyl)subnaphthalocyanines with a B-F bond are packed in a discotic hexagonal columnar phase with lattice constants a = 59-64 Å and stacking distance c = 4.7-4.8 Å. The Q-band in visible spectra of the thin film of these B-F derivatives was blue-shifted, supporting the formation of H-aggregate in stacked columns. Polarized optical microscope showed that these subnaphthalocyanines with a B-F bond exhibited mesophase at 180oC. XRD of these subnaphthalocyanines at 180 oC confirms a two dimensional hexagonal phase. XRD of the corresponding derivatives with a B-Cl bond showed that they were either amorphous or less crystalline. Figure 1

Broadband Visible Light-Absorbing [70]Fullerene-BODIPY-Triphenylamine Triad: Synthesis and Application as Heavy Atom-Free Organic Triplet Photosensitizer for Photooxidation.

A broadband visible light-absorbing [70]fullerene-BODIPY-triphenylamine triad (C70-B-T) has been synthesized and applied as a heavy atom-free organic triplet photosensitizer for photooxidation. By attaching two triphenylmethyl amine units (TPAs) to the π-core of BODIPY via ethynyl linkers, the absorption range of the antenna is extended to 700 nm with a peak at 600 nm. Thus, the absorption spectrum of C70-B-T almost covers the entire UV–visible region (270–700 nm). The photophysical processes are investigated by means of steady-state and transient spectroscopies. Upon photoexcitation at 339 nm, an efficient energy transfer (ET) from TPA to BODIPY occurs both in C70-B-T and B-T, resulting in the appearance of the BODIPY emission at 664 nm. Direct or indirect (via ET) excitation of the BODIPY-part of C70-B-T is followed by photoinduced ET from the antenna to C70, thus the singlet excited state of C70 (1C70*) is populated. Subsequently, the triplet excited state of C70 (3C70*) is produced via the intrinsic intersystem crossing of C70. The photooxidation ability of C70-B-T was studied using 1,5-dihydroxy naphthalene (DHN) as a chemical sensor. The photooxidation efficiency of C70-B-T is higher than that of the individual components of C70-1 and B-T, and even higher than that of methylene blue (MB). The photooxidation rate constant of C70-B-T is 1.47 and 1.51 times as that of C70-1 and MB, respectively. The results indicate that the C70-antenna systems can be used as another structure motif for a heavy atom-free organic triplet photosensitizer.

Reduction of Ethynylenes to Vinylenes in a Macrocyclic π-Extended Thiophene Skeleton Under McMurry Coupling Conditions.

McMurry coupling is one of the most useful and convenient tools for the preparation of π-conjugated molecules. However, for the synthesis of strained macrocycles containing ethynylene linkages, reduction of ethynylene to vinylene linkage sometimes took place. Especially, for the synthesis of macrocyclic π-extended thiophene hexamers using McMurry coupling of dialdehyde 1 composed of three thienylene, two ethynylene, and two formyl groups, reduction of ethynylenes to vinylenes often takes place to produce unique products in a one-pot procedure, depending on very small steric and electronic effects such as reaction temperature, amounts of titanium reagent, and substituents of thiophene hexamers. The attractive structures and functional properties of reduced thiophene hexamers have been determined using X-ray analysis and OFET measurements.

Fine-Tuning by Triple Bond of Carbazole Derivative Dyes to Obtain High Efficiency for Dye-Sensitized Solar Cells with Copper Electrolyte.

Three novel dyes consisting of a 5,8,15-tris(2-ethylhexyl)-8,15-dihydro-5H-benzo[1,2-b:3,4-b':6,5-b″]tricarbazole (BTC) electron-donating group and a 4,7-bis(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (BTBT) π-bridge with an anchoring group of phenyl carboxyl acid were synthesized and applied in dye-sensitized solar cells (DSCs).The AJ202 did not contain any triple bonds, the AJ201's ethynyl group was inserted between the BTC and BTBT units, and the AJ206's ethynyl group was introduced between the BTBT moiety and the anchor group. The inclusion and position of the ethynyl linkage in the sensitizer molecules significantly altered the electrochemical properties of these dyes, which can fine-tune the energy levels of the dyes. The best performing devices contained AJ206 as a sensitizer and a Cu(I/II) redox couple, which resulted in a power conversion efficiency (PCE) up to 10.8% under the standard AM 1.5 G illumination, which obtained PCEs higher than those from the devices that contained AJ201 (9.2%) and AJ202 (9.7%) under the same conditions. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels of the sensitizers were tuned to be well-suited for the Cu(I/II) redox potential and the Fermi level of TiO2. The innovative synthesis of a tricarbazole-based donor moiety in a sensitizer used in combination with a Cu(I/II) redox couple has resulted in relatively high PCEs.