Efficient Excitation Transfer Research Articles

Photoinduced Energy and Electron Transfer in a 'Two-Point' Bound Panchromatic, Near-Infrared-Absorbing Bis-styrylBODIPY(Zinc Porphyrin)2 - Fullerene Self-Assembled Supramolecular Conjugate.

Structurally well-defined self-assembled supramolecular multi-modular donor-acceptor conjugates play a significant role in furthering our understanding of photoinduced energy and electron transfer events occurring in nature, e. g., in the antenna-reaction centers of photosynthesis and their applications in light energy harvesting. However, building such multi-modular systems capable of mimicking the early events of photosynthesis has been synthetically challenging, causing a major hurdle for its growth. Often, multi-modularity is brought in by combining both covalent and noncovalent approaches. In the present study, we have developed such an approach wherein a π-extended conjugated molecular cleft, two zinc(II)porphyrin bearing bisstyrylBODIPY (dyad, 1), has been synthesized. The binding of 1 via a 'two-point' metal-ligand coordination of a bis-pyridyl fulleropyrrolidine (2), forming a stable self-assembled supramolecular complex (1 : 2), has been established. The self-assembled supramolecular complex has been fully characterized by a suite of physico-chemical methods, including TD-DFT studies. From the established energy diagram, both energy and electron transfer events were envisioned. In dyad 1, selective excitation of zinc(II)porphyrin leads to efficient singlet-singlet excitation transfer to (bisstyrly)BODIPY with an energy transfer rate constant, kEnT of 2.56×1012 s-1. In complex 1 : 2, photoexcitation of zinc(II)porphyrin results in ultrafast photoinduced electron transfer with a charge separation rate constant, kCS of 2.83×1011 s-1, and a charge recombination rate constant, kCR of 2.51×109 s-1. For excitation at 730 nm corresponding to bisstyrylBODIPY, similar results are obtained, where a biexponential decay yielded estimated values of kCS 3.44×1011 s-1 and 2.97×1010 s-1, and a kCR value of 2.10×1010 s-1. The newly built self-assembled supramolecular complex has been shown to successfully mimic the early events of the photosynthetic antenna-reaction center events.

Efficient excitation-transfer across fully connected networks via local-energy optimization

We study the excitation transfer across a fully connected quantum network whose sites energies can be artificially designed. Starting from a simplified model of a broadly-studied physical system, we systematically optimize its local energies to achieve high excitation transfer for various environmental conditions, using an adaptive Gradient Descent technique and Automatic Differentiation. We show that almost perfect transfer can be achieved with and without local dephasing, provided that the dephasing rates are not too large. We investigate our solutions in terms of resilience against variations in either the network connection strengths, or size, as well as coherence losses. We highlight the different features of a dephasing-free and dephasing-driven transfer. Our work gives further insight into the interplay between coherence and dephasing effects in excitation-transfer phenomena across fully connected quantum networks. In turn, this will help designing optimal transfer in artificial open networks through the simple manipulation of local energies.

Efficient Electronic Excitation Transfer via Phonon-Assisted Dipole-Dipole Coupling inFe2+:Cr2+:ZnSe

${\mathrm{Cr}}^{2+}$ - and ${\mathrm{Fe}}^{2+}$ -doped $\mathrm{Zn}\mathrm{Se}$ crystals are laser materials with phonon-broadened absorption and emission spectra, which provide broadband laser gain in the 2- to 5-$\text{\ensuremath{\mu}}\mathrm{m}$ wavelength range. While ${\mathrm{Cr}}^{2+}\text{:ZnSe}$ can be directly pumped with high-power Er, Ho, or Tm lasers, no such possibility exists for ${\mathrm{Fe}}^{2+}\text{:ZnSe}$. To this end, electronic excitation transfer between ${\mathrm{Cr}}^{2+}$ and ${\mathrm{Fe}}^{2+}$ ions in codoped ZnSe is investigated as an alternative excitation process in photo luminescence (PL) experiments with sub-10-ns temporal resolution. For a wide range of ion concentrations, we observe nonexponential decays of ${\mathrm{Cr}}^{2+}$ PL on a microsecond time scale, a 60-ns rise time of ${\mathrm{Fe}}^{2+}$ PL at high doping densities, and a prolonged decay of ${\mathrm{Fe}}^{2+}$ PL due to the temporal characteristics of excitation transfer over a range of interionic distances. Using a multirate equation model, the transfer process is analyzed on length scales up to 30 nm and compared to the established continuum model approach. The analysis reveals an unexpectedly efficient excitation transfer from ${\mathrm{Cr}}^{2+}$ to ${\mathrm{Fe}}^{2+}$ ions with an enhancement of the excitation transfer rates by up to a factor of 5 in comparison to resonant dipole-dipole coupling. The enhancement is assigned to (multi)phonon-assisted excitation transfer, in analogy to the phonon-mediated efficient radiationless decay of the excited ${\mathrm{Fe}}^{2+}$ state. As nonradiative losses and excitation transfer show different temperature scaling, a cryogenic temperature regime is found that promises overall efficiencies above 50%, making ${\mathrm{Fe}}^{2+}:{\mathrm{Cr}}^{2+}\text{:ZnSe}$ a much more viable alternative to parametric conversion schemes in the midinfrared range.

A novel TiO2-x/TiN@ACB composite for synchronous photocatalytic Cr(VI) reduction and water photothermal evaporation under visible/infrared light illumination

Relatively large band-gap, fast charge carriers recombination, and mono-functionality of photocatalytic materials are still representing stumbling hurdles against their optimal usage for water cleaning. Herein, a novel black titanium oxide/plasmonic titanium nitride@activated coconut biochar (TiO2-x/TiN@ACB) composite was designed to have both photocatalytic and photothermal functions. Intermediate states of black TiO2-x, plasmonic effect of TiN, and high electrons (e−) capacity of biochar enhanced band-gap narrowing, light absorbance extension, and charge carriers separation respectively. Black TiO2-x and plasmonic TiN sensitization via visible/infrared (Vis/IR) portion of photonic spectrum in addition to the confirmed close contact of composite constituents explained the demonstrated major role of e− in photocatalytic mechanism through efficient excitation and facile transfer. Thanks to black photocatalytic semiconductor and carbonic materials for their ultimate photons harnessing and efficient photothermal conversion where the composite exhibited a remarkable photothermal water evaporation upon Vis/IR illumination as well. TiO2-x/TiN@ACB composite revealed 92.8 and 89.7% photocatalytic reduction of hexavalent chromium (Cr(VI)) and water evaporation efficiencies up to 92.9 and 51.1% upon IR and Vis light illumination respectively. This study proposes a new approach for efficient water cleaning by coupling of oxygen deficient and plasmonic semiconductors supported on naturally derived carbonic material as a broad spectrum harvester and bi-functional photocatalytic and photothermal material.

Efficient and robust collective excitation transfer in a multimode quantum memory using modulated adiabatic pulses

Quantum memories are building blocks for a variety of quantum technologies. However, the collective transfer between optical excitations and spin-wave excitations determines the performance of the quantum memory. Here we propose a method for collective excitations transfer with high efficiency and fidelity in a multimode quantum memory. The pulse uses modulations of the control parameters to cancel the nonadiabatic transitions during the evolution. We demonstrate the universality of the control pulse by simulations for an atomic frequency comb spin-wave quantum memory. The protocol is robust to various experimental imperfections in the pulse amplitude and duration. The protocol also allows one to achieve high multiplexed storage at small cost on efficiency reduction. The protocol is particularly useful in retaining the phase coherence since the environment dissipation would decohere the system. These results pave a way for efficient and robust coherent manipulations in a multiplexed quantum memory.

Luminescent Hybrid Materials Based on Polymers of Poly(Alpha-Fluoroacrylates) Doped with Tb(III) Complex

This study is devoted to the development of efficient luminescent hybrid materials excited by UV radiation and featuring narrow luminescence lines as well as light, humidity, and temperature resistance. As a luminescent material, a terbium ion coordination compound introduced into the matrix of an organofluorine polymer is used. It has been shown that efficient excitation transfer to electronic levels of the terbium ion can be achieved by proper ligand selection. The polymer matrix material does not affect the luminescence properties of the Tb(III) coordination compound.

Improvement of spectroscopic properties and luminescence of Er3+ions in phospho-tellurite glass ceramics by formation of ErPO4 nanocrystals

Er3+ doped phospho-tellurite glass was prepared by melt-quenching method. A limited partial crystallization of the glass samples was controlled by thermal annealing process in order to obtain a transparent glass-ceramic. The X-ray diffraction (XRD) patterns indicate the precipitation of nanocrystalline phases after heat treatment. A particular interest is devoted to the formation of ErPO4 nanoparticles (NPs) dispersed in the glassy host. The optical band gap (Eg) has been found to decrease from 3.37 to 2.75eV as the sample changes from glass to glass-ceramic. The Judd–Ofelt (JO) phenomenological intensity parameters (Ω2, Ω4, Ω6) have been estimated by means of the absorption spectrum. Radiative parameters of Er3+ ions have been predictedusing JO intensity parameters. Significant improvements of both the near infrared emission relative to the 4I13/2 → 4I15/2 transition and the corresponding luminescence lifetime were obtained after heat treatment. We show that an efficient excitation transfer occurs from the formed ErPO4 NPs to Er3+ ions. The Mc-Cumber method is used to calculate the absorption cross-section σa, the emission cross-section σe and the gain cross-section G(λ) relative to the 4I13/2 → 4I15/2 transition.Compared with other glass hosts, the results indicate that erbium doped phospho-tellurite glass-ceramic has good prospect as a gain medium applied for 1.53 μm band broad and high-gain erbium-doped fiber amplifiers (EDFA).

(Invited) Perylene-Based Functionalization of Carbon Nanotubes

Functionalization aims at granting compounds with additional features. This is achieved by typically attaching novel groups to the original systems. The aftermath of such process yields complexes whose charcteristics often result in more than just the mere sum of the initial products. The specific character of the functionalized structure, moreover, depends upon the way the functionalization strategy has been pursued. We will focus on the carbon nanotubes functionalization through perylene, an aromatic molecule emitting in the excitation window of most single-walled nanotubes commercially available. We have previously shown that the perylene core of custom surfactants was able to attach though pi-pi stacking interactions onto the sidewall of CNTs while ensuring efficient excitation transfer to the tubes [1,2]. Here we will show how starting from the same elements (perylene and nanotubes) and pursuing different functionalization routines, we achieve systems with different features and functions. In particular, we will compare the characteristics of perylene-comprising polymers wrapped around the tubes [3] with the peculiarities of perylene covalently attached to the nanotubes following a novel conjugation-preserving routine we recently developed [4]. We will highlight the difference among the properties of the final products as well as the applications they would be suitable for. [1] F Ernst et al., Adv. Funct. Mat. 2012, 22, 3921. [2] F Ernst et al., Appl. Phys. Lett. 2013, 102, 233105. [3] K. Huth et al, Small 2018, 14, 1800796. [4] A Setaro et al. Nat. Comm. 2017, 8, 14281.

Dark states and delocalization: Competing effects of quantum coherence on the efficiency of light harvesting systems.

Natural light harvesting systems exploit electronic coupling of identical chromophores to generate efficient and robust excitation transfer and conversion. Dark states created by strong coupling between chromophores in the antenna structure can significantly reduce radiative recombination and enhance energy conversion efficiency. Increasing the number of the chromophores increases the number of dark states and the associated enhanced energy conversion efficiency yet also delocalizes excitations away from the trapping center and reduces the energy conversion rate. Therefore, a competition between dark state protection and delocalization must be considered when designing the optimal size of a light harvesting system. In this study, we explore the two competing mechanisms in a chain-structured antenna and show that dark state protection is the dominant mechanism, with an intriguing dependence on the parity of the number of chromophores. This dependence is linked to the exciton distribution among eigenstates, which is strongly affected by the coupling strength between chromophores and the temperature. Combining these findings, we propose that increasing the coupling strength between the chromophores can significantly increase the power output of the light harvesting system.

Flicker Reduction of AC LEDs by Mn2+ Doped Apatite Phosphor

This work presents some flicker reducing phosphors according to the composition Sr5(PO4)3Cl:Eu2+Mn2+, which are excitable between 380 and 450 nm and exhibit an emission spectrum ranging from 550 to 620 nm. Flicker is defined as “the rapid variation in light source intensity” and it is still a drawback of modern AC driven LEDs, which are not electrically smoothened by a driver. Recently, a lot of effort is dedicated to the electrical smoothening of LED flicker. Instead of using a driver system, this work concentrates on a phosphor, which emits light during the dead time of the LED chip. Due to the slow decay of the forbidden transition of Mn2+ and an efficient excitation transfer from Eu2+ to Mn2+ a white light emitting LED system with a percent flicker of about 30% and a flicker index of 0.08 was achieved. A white color point was created by using an optimized doping concentration of Eu2+ and Mn2+ in the Sr5(PO4)3Cl:Eu2+Mn2+ and a 400 nm LED as excitation source.

Panchromatic Light Capture and Efficient Excitation Transfer Leading to Near-IR Emission of BODIPY Oligomers.

All-BODIPY-based (BODIPY=boron-dipyrromethene) donor-acceptor systems capable of wide-band absorbance leading to efficient energy transfer in the near-IR region are reported. A covalently linked 3-pyrrolyl BODIPY-BODIPY dimer building block bearing an ethynyl group at the meso-aryl position is synthesized and coupled with three different monomeric BODIPY/pyrrolyl BODIPY building blocks with a bromo/iodo group under Pd(0) coupling conditions to obtain three covalently linked 3-pyrrolyl-BODIPY-based donor-acceptor oligomers in 19-29 % yield. The oligomers are characterized in detail by 1D and 2D NMR spectroscopy, high-resolution mass spectrometry, and optical spectroscopy. Due to the presence of different functionalized BODIPY derivatives in the oligomers, panchromatic light capture (300-725 nm) is witnessed. Fluorescence studies reveal singlet-singlet energy transfer from BODIPY monomer to BODIPY dimer leading to emission in the 700-800 nm range. Theoretical modeling according to the Förster mechanism predicts ultrafast energy transfer due to good spectral overlap of the donor and acceptor entities. Femtosecond transient absorption studies confirm this to be the case and thus show the relevance of the currently developed all-BODIPY-based energy-funneling supramolecular sytems with near-IR emission to solar-energy harvesting applications.

Dissipation-enabled efficient excitation transfer from a single photon to a single quantum emitter

We propose a scheme for triggering a dissipation dominated highly efficient excitation transfer from a single photon wave packet to a single quantum emitter. This single photon induced optical pumping turns dominant dissipative processes, such as spontaneous photon emission by the emitter or cavity decay, into valuable tools for quantum information processing and quantum communication. It works for an arbitrarily shaped single photon wave packet with sufficiently small bandwidth provided a matching condition is satisfied which balances the dissipative rates involved. Our scheme does not require additional laser pulses or quantum feedback and is not restricted to highly mode selective cavity quantum electrodynamical architectures. In particular, it can be used to enhance significantly the coupling of a single photon to a single quantum emitter implanted in a one dimensional waveguide or even in a free space scenario. We demonstrate the usefulness of our scheme for building a deterministic quantum memory and a deterministic frequency converter between photonic qubits of different wavelengths.

Energy Transfer Dye Laser Study of Influence of Various Coumarin Dyes on the Laser Performance of Rh590(Cl) Dye

Different coumarin dyes(C440, C460, C480, C485, C500 and C540A) are mixed with Rh590(Cl) in ethanol. The effect of coumarin dyes and their concentration on the laser gain properties and photostabilities of Rh590(Cl) is studied and discussed by investigating the gain characteristics at various concentrations and pump powers of N2–laser. It is found that for C480 and C540A dyes at optimized concentration, most of the absorbed pump power is transferred to Rh590(Cl) as a useful pump power. The gain characteristics of Rh590(Cl)are found to be changed due to change in the fluorescence lifetime. The mechanism responsible for the improvement in the laser performance and gain characteristics of Rh590(Cl) resulted from the energy transfer from these coumarin dyes. This improvement in the laser efficiency of Rh590(Cl) varied sharply depending upon the kind of coumarin dye. The theoretical calculations are also done to find the total transfer efficiency at various donor concentrations to identify the appropriate energy transfer mechanism responsible for gain enhancement in Rh590(Cl) dye. These calculations take into account the contribution due to both radiative and non radiative energy transfer. In these dye mixtures the energy transfer excitation was found to overcome the inner filter effect and other losses such as photoquenching. The concentration dependence of peak gain and the lasing wavelengths of ETDL have been studied. The experimental results indicate that the dominant mechanism responsible for the efficient excitation transfer in these mixtures is of non radiative nature due to long range dipole-dipole interaction. A broader tunable range is also provided by energy transfer.

Effect of Mn doping on structural, optical and photocatalytic behaviors of hydrothermal Zn1−xMnxS nanocrystals

Undoped and Mn-doped ZnS nanocrystals (Ncs) have been synthesized by using the hydrothermal method at 200°C. X-ray diffraction (XRD) patterns revealed that the synthesized Ncs have cubic zinc blende structure. Typical SEM images show that undoped and Mn-doped ZnS Ncs are agglomerated in microspheres. Raman spectra informed that the Mn doping has improved the crystallinity of the ZnS Ncs up to the concentration 3%. The optical properties of Mn-doped ZnS Ncs were studied through UV–vis diffuse reflection spectroscopy, photoluminescence (PL), PL decay and PL excitation (PLE) measurements. The optical band gap was found to decrease from 3.59 to 3.35eV with increasing the Mn doping concentration. PL spectra demonstrate clearly that Mn2+ ions reduce the density of defect in both ZnS lattice and surface. An efficient excitation transfer from the ZnS host to Mn2+ ions is evidenced from PL decays.ZnS:Mn Ncs were found to be good photocatalyst for sunlight degradation of Rhodamine B. The optimum Mn dopant concentration was 3%, above which photocatalytic activity decreased. The degradation reaction obeyed pseudo-first-order kinetics.

Experimental evidence of resonant energy collisional transfers between argon 1s and 2p states and ground state H atoms by laser collisional induced fluorescence

In this paper, laser collisional induced fluorescence (LCIF) is used to probe resonant excitation transfers in an argon/hydrogen plasma resulting from heavy particle collisions. Different radiative transitions between the 1s and 2p states (in Paschen's notation) of argon are optically pumped by a nanosecond laser pulse. The spontaneous fluorescence and collisional responses of the argon and hydrogen systems are monitored by optical emission spectroscopy. A surfatron plasma source is used to generate an argon plasma with a few per cent hydrogen addition at pressures between 0.65 and 20 mbar. The electron density is measured independently by means of Thomson scattering.The overall response of the plasma due to optical pumping of argon is briefly discussed and an overview of the known heteronuclear excitation transfers in an argon/hydrogen plasma is given. The propagation of the shortcut in the Ar(1s) to H(n = 2) excitation transfer due to the optical pumping of the Ar(1s) states is seen in the atomic hydrogen LCIF responses. For the first time, we give direct experimental evidence of the existence of an efficient excitation transfer:Additionally, measurements are performed in order to estimate the resonant energy transfer between the resonant argon 1s states and hydrogen atoms:for which no previously measured cross sections could be found in the literature. These are extra quenching channels of argon 1s and 2p states that should be included in collisional–radiative modeling of argon–hydrogen discharges. The high repetition rate of the dye laser allows us to obtain a high sensitivity in the measurements. LCIF is shown to be a powerful tool for unraveling electron and also heavy particle excitation channels in situ in the plasma phase. The technique was previously developed for measuring electron or species densities locally in the plasma, but we show that it can be advantageously used to probe collisional transfers between very short-lived species which exist simultaneously only in the plasma phase.

Control of excitation transfer in coupled quantum dots by a nonresonant laser pulse

Abstract We study theoretically fast transfer of excitons between pairs of coupled quantum dots driven by the optical Stark effect that is produced by a short nonresonant laser pulse. The Schrodinger equation, in which the relative position of energy levels of quantum dot subsystems is time-dependent, is solved numerically. Computer simulation demonstrates the mechanism of controlling the efficient excitation transfer by the action of a picosecond laser pulse with a flat-top intensity profile.

Interacting dark resonances with plasmonic meta-molecules

Dark state physics has led to a variety of remarkable phenomena in atomic physics, quantum optics, and information theory. Here, we investigate interacting dark resonance type physics in multi-layered plasmonic meta-molecules. We theoretically demonstrate that these plasmonic meta-molecules exhibit sub-natural spectral response, analogous to conventional atomic four-level configuration, by manipulating the evanescent coupling between the bright and dark elements (plasmonic atoms). Using cascaded coupling, we show nearly 4-fold reduction in linewidth of the hybridized resonance compared to a resonantly excited single bright plasmonic atom with same absorbance. In addition, we engineered the geometry of the meta-molecules to realize efficient intramolecular excitation transfer with nearly 80%, on resonant excitation, of the total absorption being localized at the second dark plasmonic atom. An analytical description of the spectral response of the structure is presented with full electrodynamics simulations to corroborate our results. Such multilayered meta-molecules can bring a new dimension to higher quality factor plasmonic resonance, efficient excitation transfer, wavelength demultiplexing, and enhanced non-linearity at nanoscale.

Excitons in the LH3 Complexes from Purple Bacteria

The noncovalently bound and structurally identical bacteriochlorophyll a chromophores in the peripheral light-harvesting complexes LH2 (B800-850) and LH3 (B800-820) from photosynthetic purple bacteria ensure the variability of the exciton spectra in the near-infrared (820-850 nm) wavelength region. As a result, the spectroscopic properties of the antenna complexes, such as positions of the maxima in the exciton absorption spectra, give rise to very efficient excitation transfer toward the reaction center. In this work, we investigated the possible molecular origin of the excitonically coupled B820 bacteriochlorophylls in LH3 using femtosecond transient absorption spectroscopy, deconvolution of steady-state absorption spectra, and modeling of the electrostatic intermolecular interactions using a charge density coupling approach. Compared to LH2, the upper excitonic level is red-shifted from 755 to 790 nm and is associated with an approximate 2-fold decrease of B820 intrapigment coupling. The absorption properties of LH3 cannot be reproduced by only changing the B850 site energy but also require a different scaling factor to be used to calculate interpigment couplings and a change of histidine protonation state. Several protonation patterns for distinct amino acid groups are presented, giving values of 162-173 cm(-1) at 100 K for the intradimer resonance interaction in the B820 ring.

Two-Dimensional Electronic Spectroscopy Reveals Ultrafast Energy Diffusion in Chlorosomes

Chlorosomes are light-harvesting antennae that enable exceptionally efficient light energy capture and excitation transfer. They are found in certain photosynthetic bacteria, some of which live in extremely low-light environments. In this work, chlorosomes from the green sulfur bacterium Chlorobaculum tepidum were studied by coherent electronic two-dimensional (2D) spectroscopy. Previously uncharacterized ultrafast energy transfer dynamics were followed, appearing as evolution of the 2D spectral line-shape during the first 200 fs after excitation. Observed initial energy flow through the chlorosome is well explained by effective exciton diffusion on a sub-100 fs time scale, which assures efficiency and robustness of the process. The ultrafast incoherent diffusion-like behavior of the excitons points to a disordered energy landscape in the chlorosome, which leads to a rapid loss of excitonic coherences between its structural subunits. This disorder prevents observation of excitonic coherences in the experimental data and implies that the chlorosome as a whole does not function as a coherent light-harvester.

Supramolecular Donor–Acceptor Assembly Derived from Tetracarbazole–Zinc Phthalocyanine Coordinated to Fullerene: Design, Synthesis, Photochemical, and Photoelectrochemical Studies

A functional photosynthetic antenna–reaction center mimicking donor–acceptor polyad has been newly designed, synthesized, and characterized. The polyad was comprised of four entities of carbazole covalently linked to the macrocycle periphery of a zinc phthalocyanine (ZnPc). Efficient singlet excitation transfer from the carbazole to zinc phthalocyanine has been witnessed from the emission studies. Axial coordination of phenylimidazole-functionalized fulleropyrrolidine to ZnPc served as an electron acceptor in the polyad. Optical absorption and emission along with computational studies revealed stable complex formation wherein the evaluated binding constant K was 7.7 ± 0.2 × 105 M–1, an order of magnitude higher than that observed earlier for similar complexes due to the electronic effect induced by the carbazole entities. From the free-energy calculations, photoinduced electron transfer from the 1ZnPc* to fullerene within the polyad was established to be an exothermic process. Kinetics of charge separation, kCS, monitored by time-resolved emission was found to be 2.8 × 109 s–1, indicating a relatively fast charge-separation process. The electron-transfer products were characterized by nanosecond transient absorption spectroscopic technique; the presence of ZnPc+• radical cation at 890 nm and fulleropyrrolidine anion radical at 1000 nm was clear from this study. The kinetics of charge recombination, kCR, evaluated from the decay of either of the radical ions, was found to be 6.25 ± 0.2 × 107 s–1, revealing the persistence of the radical ion-pair species to some extent. Further, photoelectrochemical studies, performed by constructing photocells by electrophoretic deposition of the studied polyad on nanocrystalline SnO2 modified surface, revealed a higher value of incident photon-to-current conversion efficiency covering the wide visible–near IR spectral region and good on–off switchability. Better charge injection from the excited polyad to the conduction band of the semiconductor was evident from the electrochemical impedance spectral measurements of electron recombination resistance calculations.