Light Energy Harvesting Research Articles

Performance Evaluation of Non-Lambertian SLIPT for 6G Visible Light Communication Systems

Visible light communication (VLC) has emerged as one promising candidate technique to improve the throughput performance in future sixth-generation (6G) mobile communication networks. Due to the limited battery capacity of VLC systems, light energy harvesting has been proposed and incorporated for achieving the simultaneous lightwave information and power transfer (SLIPT) function and for improving the overall energy efficiency. Nevertheless, almost all reported works are limited to SLIPT scenarios adopting a basic and well-discussed Lambertian optical transmitter, which definitely cannot characterize the potential and essential scenarios employing distinctive non-Lambertian optical transmitters with various spatial beam characteristics. For addressing this issue, in this work, SLIPT based on a distinct non-Lambertian optical beam configuration is investigated, and for further enhancing the harvested energy and the achievable data rate, the relevant flexible optical beam configuration method is presented as well. The numerical results show that, for a typical receiver position, compared with about 1.14 mJ harvested energy and a 31.2 Mbps achievable data rate of the baseline Lambertian configuration, a harvested energy gain of up to 1.55 mJ and an achievable data rate gain of 21.1 Mbps can be achieved by the non-Lambertian SLIPT scheme explored here.

Light energy harvested flexible wireless sensing for disinfection sterilization in food storage

Cold chain logistics involves all aspects of food storage, transport, and sales. This study focuses on innovating cold storage disinfection within this context. Regular disinfection reduces microorganism growth, improves food quality, and ensures safety. Traditional methods lack automation, accurate monitoring, and responsive control. Conventional sensors are unsuitable for curved bottles and need frequent power changes. This paper proposes a light energy harvested flexible wireless sensing for disinfection sterilization in food storage (FLWDS). FLWDS comprises five parts: light energy harvesting and power supply node (LEPN), sensing node, control node, monitoring node, and host computer. A predictive control model improves response speed and accuracy. Bluetooth technology ensures real-time communication between nodes. FLWDS collects light energy inside the cold store as a supplementary energy source and can be used in curved structures with a response time of less than 1 s. The maximum communication distance is 40 m. The flexible level sensing system can be designed according to the induction pad’s length, with a measurement accuracy of 0.3 mm, sampling every 4.8 ms, and a resolution of 0.2 mm. FLWDS provides self-powered flexible wireless sensing, ensuring accurate liquid level measurement, improved food quality, reduced pollution, and increased sustainability.

Symmetry Breaking Charge Separation in Far-Red Absorbing Bisstyryl-Bodipy Dimers

Symmetry breaking charge transfer is one of the important photo-events occurring in photosynthetic reaction centers that is responsible for initiating electron transfer leading to a long-lived charge-separated state and has been successfully employed in light-to-electricity converting optoelectronic devices. Here, we report the synthesis of far-red absorbing and emitting BODIPY-dimer to undergo symmetry-breaking charge transfer leading to charge-separated states of appreciable lifetimes in polar solvents. Compared to its monomer analog, both steady-state and time-resolved fluorescence originating from the S1 state of the dimer revealed quenching which increased with an increase in solvent polarity. The electrostatic potential map from DFT and the time-dependent DFT calculations suggested the existence of a quadrupolar type charge transfer state in polar solvents, and the singlet excited state to be involved in the charge separation process. The electrochemically determined redox gap to be smaller than the energy of the S1 state supporting thermodynamic feasibility of the envisioned symmetry-breaking charge transfer and separation. The spectrum of the charge-separated state arrived from spectroelectrochemical studies, revealing diagnostic peaks helpful for transient spectral interpretation. Finally, ultrafast transient pump-probe spectroscopy provided conclusive evidence of diabatic charge separation in polar solvents by far-red pulsed laser light irradiation. The measured lifetime of the final charge-separated states was found to be 165 ps in dichlorobenzene, 140 ps in benzonitrile, and 43 ps in dimethyl sulfoxide, revealing their significance in light energy harvesting, especially from the less-explored far-red region.

(Invited) A CNT Binding Bis(Zinc Porphyrin)Bodipy-C60 Nano Tweezer: Charge Stabilization in Supramolecular C60-Bodipy-(ZnP)2:SWCNT Hybrids

Single-wall carbon nanotubes (SWCNT) coupled with either electron donor or acceptor are promising functional structures for light energy harvesting and molecular optoelectronics applications. For building such hybrids involving SWCNTs, the p-stacking ability of large aromatic compounds is one of the commonly employed approaches.1-2 Often, the desired donor or acceptor entities are functionalized to carry one or more aromatic entities and allowed to interact with CNTs. However, due to close proximity, the role of SWCNTs in stabilizing the electron transfer product has been a challenge.3 Recently, we overcame this hurdle by employing a multi-modular approach to build donor-acceptor hybrids and successfully demonstrated charge stabilization in the presence of SWCNTs.4 In the present study, we have further improved our design by newly synthesizing a nano tweezer comprised of covalently linked BODIPY-C60 carrying two zinc porphyrin arms as shown in the figure. This compound was further allowed to interact with SWCNT(6,5) and SWCNT(7,6) to form the supramolecular C60-BODIPY-(ZnP)2:SWCNThybrids. Upon spectral, electrochemical, and computational characterization, femtosecond pump-probe spectroscopic studies were performed to establish the occurrence of photoinduced charge separation and charge stabilization. Extending the lifetime of the charge-separated states upon SWCNT binding has been successfully demonstrated in the present molecular design strategy. D’Souza, F.; Sandanayaka, A. S. D.; Ito, O. ‘SWNT-Based Supramolecular Nanoarchitectures with Photosensitizing Donor and Acceptor Molecules’ Phys. Chem. Letts. 2010, 1. 2586-2593.B. KC, G. N. Lim, and F. D’Souza, ‘Accelerated Charge Separation in Graphene Decorated Multi-Modular Tripyrene-Subphthalocyanine-Fullerene Donor-Acceptor Hybrids,’ Angew. Chem. Int. Ed. 2015, 54, 5088-5092.Barrejon, L. M. Arellano, F. D’Souza, F. Langa, ‘Bidirectional charge transfer in carbon-based hybrid nanomaterials’ Nanoscale, 2019, 11, 14978-14992.Kazemi, Y. Jang, A. Liyanage, P. A. Karr, and F. D’Souza, A Carbon Nanotube Binding Bis(pyrenylstyryl)BODIPY-C60 Nano Tweezer: Charge Stabilization through Sequential Electron Transfer, Angew. Chem. Int. Ed. 2022, 61, e202212474 (1-7). Figure 1

(Invited) Non-Fullerene Acceptor in Organic Solar Cells Toward Improving Performance as Indoor Light Energy Harvester

Research in organic solar cells aims to develop new materials that improve efficiency. The inception of emerging non-fullerene acceptors (NFAs) by replacing the fullerene counterpart in organic solar cells (OSCs) has pushed the bulk-heterojunction based photovoltaics to achieve efficiencies around 18% [1-6]. In order to produce efficient OSCs, it is required to have donor and acceptor materials with matching absorption bands in the Vis-NIR range, high charge-carrier mobility, and a small energy offset to minimize voltage losses. Mainly, the development of Y7 NFA molecule has improved power conversion efficiencies by pairing selected polymer donors, such as PM6 [7, 8]. Nowadays, OSCs have attracted great attention for being used as indoor light energy harvesters. The organic materials in the active layer can have tuned optical band gaps, providing an absorption spectrum that matches with emission spectra of several indoor lights, e.g., halogen lights, LED (light-emitting diodes), and FLs (fluorescent lamp), which have different emitting spectra [9, 10].The use of OSCs for indoor light harvesting applications is promising for integration into low-power indoor electronic devices from microwatts to milliwatts, such as data transfer systems, alarm systems and distributed controls. Moreover, the OSCs have the possibility to be used with power wireless sensor nodes connected to the Internet of Things. At present, LEDs are the most popular low-light level sources which can be found in offices and homes. The intensity of the light emitted by an artificial light source, per unit area of a surface is called illuminance and measured in units of lux (lx). A level 500 lx is typically recommended for office environments and 200 lx for living room environments.In this research, we have been aiming at the performance and stability over time of organic solar cells under LED illumination using fullerene and non-fullerene acceptors. We have chosen as the indoor illumination source an LED lamp with a color temperature of 3000 K and color rendering index (CRI) > 80 following the protocols ISOS [11]. The LED lamp output illuminances were varied in the range from 200 to 1500 lx. We have used PM6 as polymer donor material due to their absorption spectrum and energy band gaps well-matched to the incident LED spectrum. In order to research the improvement of the performance of OSCs under indoor illumination we have compared PC70BM fullerene acceptor with ITIC-M, Y6-O, and Y7 non-fullerene acceptors. As a result, under 1000 lx illumination we achieved PCEs from ~ 12% using Y6-O, ~ 15% using PC70BM, ~16% using Y7 up to more than 18% efficiency using ITIC-M. The study is performed including optical and electrical characterization with the purpose of understanding the behavior and the transport processes taking place in the device. In future work, we focus on the stability of the encapsulated OSCs under continuous LED illumination following the agreed stability testing protocols to study which active layer turns out to be more stable under these conditions. Acknowledgements: This work was supported by the Ministerio de Ciencia, Innovación y Universidades (MICINN/FEDER) PDI2021-128342OB-I00, by the Agency for Management of University and Research Grants (AGAUR) ref. 2021-SGR-00739, and by the Catalan Institution for Research and Advanced Studies (ICREA) under the ICREA Academia Award. M. Ramírez-Como acknowledge to CONAHCYT ref. BPPA-20220624083033039-2364083.

What Makes a Photobattery Light-Rechargeable?

The demand for autonomous off-grid devices has led to the development of "photobatteries", which integrate light-energy harvesting and electrochemical energy storage in the same architecture. Despite several photobattery chemistries and designs being reported recently, there have been few insights into the physical conditions necessary for charge transfer between the photoelectrode and counter electrode. Here, we use a three-electrode photobattery with a dye-sensitized TiO2 photoelectrode, triiodide (I-/I3 -) catholyte, and anodes with varying intercalation potentials to confirm that photocharging is only feasible when the conduction band quasi-Fermi level (EFc) is positioned above the anode intercalation/plating potential. We also show that parasitic reactions after the battery is fully charged can be accelerated if the voltage of the battery and solar cell are not matched. The integration of multiple anodes in the same photobattery ensures well-controlled measurement conditions, allowing us to demonstrate the physical conditions necessary for charge transfer in photobatteries, which has been a topic of controversy in the field.

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.

Design and Performance Evaluation of the Energy Subsystem of a Hybrid Light and Wave Energy Harvester

Design and Performance Evaluation of the Energy Subsystem of a Hybrid Light and Wave Energy Harvester

Unveiling the potential of bifacial photovoltaics in harvesting indoor light energy: A comprehensive review

Bifacial photovoltaics (BPVs) have received tremendous attention as a potential contender for efficient and cost-effective light energy harvesting. Recently, advancements in BPV technologies have broadened their scope, allowing them to harness artificial indoor light energy efficiently from both top and bottom sides. This innovative approach has demonstrated its effectiveness in energy harvesting through a single-cell design. Among various available PV technologies, thin-film perovskite photovoltaics (PPVs) exhibit exceptional promise for indoor applications in low-light environments. They offer high-power conversion efficiency and ease of design, making them a superior choice when compared to other emerging indoor PV technologies such as kesterite and dye-sensitized PVs. To improve the performance of the indoor BPVs, it is necessary to further review several characteristics relating to their materials, architecture, processing, and indoor characterizations. Additionally, a comprehensive understanding of charge-transfer mechanisms, the variability in indoor lighting sources, the development of standardized indoor simulators, assessment of materials toxicity, and considerations of scalability are essential elements that must be addressed to advance this technology. In summary, this review examines recent developments, emerging trends, challenges, and provide suggestions for the further advancement of i-BPVs, also highlighting their potential as reliable and sustainable indoor energy-harvesting solution.

Electron Donor‐Acceptor (EDA) Complex Enabled C−C Cross‐Coupling Reactions of α‐Amino Radicals

AbstractElectron‐donor acceptor (EDA) complex has been an integral part of visible‐light photocatalysis and is different from the traditional photoredox catalysis, which requires an exogenous photocatalyst, typically a colored compound to initiate the photocatalytic cycle. Interestingly, the EDA‐complex photochemistry has found profound use in activating the inert α‐C−H bonds of amines. The strategy relied upon the formation of colored EDA‐complex between the donor (amine) and acceptor (Lewis acid), which upon harvesting light energy perform a SET process to generate radical cation and anion intermediates. The radical cation then loses the activated acidic proton (because of the SET, the acidity of α‐proton increases by lowering the BDE) to form α‐amino radical, which then participates in various C−C coupling cascades. In this review, different conceptual approaches for the generation of α‐amino radicals and their coupling for the C−C bond‐forming reaction under EDA‐complex triggered photocatalysis will be discussed with particular emphasis on the reaction mechanism from 2018 onwards.

Application of quantum dot light-emitting diode harvest by quantum dot solar cells

Recent progress in photovoltaic (PV) cell usage has been hindered due to a shortage of suitable materials that emit adequate wavelengths of light energy and convert it to electricity. Quantum dot light-emitting diodes (QLEDs) and quantum dot solar cells (QDSCs) have been identified as promising artificial light sources and PV cell types to nicely fit into this solution, not only complying with that but also being controllable, flexible, portable, and lightweight. The purpose of this study is to provide a review of the application of how QLEDs can be collected for QDSCs. First, we introduce QLEDs as artificial light sources, briefly outline their mechanics and benefits, and compare them to other light sources for QDSC harvesting. Then, we summarize the mechanisms that occur when a QDSC absorbs a photon from a QLED, as well as how these energy flow pathways influence artificial light energy harvest. Finally, we explore the optoelectronic properties of lead sulphide (PbS) and lead selenide (PbSe) as appropriate quantum dots (QDs) materials for current applications in QDSC and QLED technologies. We anticipate that the literature will be comprehensive and relevant to the scientific community interested in creating artificial light energy harvesting and thus researching the most recent alternative method of getting healthy energy.

Multimodular Wide-Band Capturing Nanohybrids: Role of Carbon Nanotubes in Slowing Charge Recombination in Supramolecular C60-BisstyrylBODIPY-(Zinc Porphyrin)2 Donor-Acceptor Molecular Cleft.

The importance of diameter-sorted single-wall carbon nanotubes (SWCNTs) noncovalently bound to a donor-acceptor molecular cleft, 1, in prolonging the lifetime of charge-separated states is successfully demonstrated. For this, using a multistep synthetic procedure, a wide-band capturing, multimodular, C60-bisstyrylBODIPY-(zinc porphyrin)2, molecular cleft 1, was newly synthesized and shown to bind diameter-sorted SWCNTs. The molecular cleft and its supramolecular assemblies were characterized by a suite of physicochemical techniques. Free-energy calculations suggested that both the (6,5) and (7,6) SWCNTs bound to 1 act as hole acceptors during the photoinduced sequential electron transfer events. Consequently, selective excitation of 1 in 1:SWCNT hybrids revealed a two-step electron transfer, leading to the formation of charge-separated states. Due to the distant separation of the cation and anion radical species within the supramolecules, improved lifetimes of the charge-separated states could be achieved. The present supramolecular strategy of improving charge separation involving SWCNTs and donor-acceptor molecular clefts highlights the potential application of these hybrid materials for various light energy harvesting and optoelectronic applications.

A new bacterial consortia for management of Fusarium head blight in wheat

Fusarium head blight (FHB) is a significantly important disease in cereals primarily caused by Fusarium species. FHB control is largely executed through chemical strategies, which are costlier to sustainable wheat production, resulting in leaning towards sustainable sources such as resistance breeding and biological control methods for FHB. The present investigation was aimed at evaluating newly identified bacterial consortium (BCM) as biocontrol agents for FHB and understanding the morpho-physiological traits associated with the disease resistance of spring wheat. Preliminary evaluation through antagonistic plate assay and in vivo assessment indicated that BCM effectively inhibited Fusarium growth in spring wheat, reducing area under disease progress curve (AUDPC) and deoxynivalenol (DON), potentially causing type II and V resistance, and improving single spike yield (SSPY). Endurance to FHB infection with the application of BCM is associated with better sustenance of spike photosynthetic performance by improving the light energy harvesting and its utilization. Correlation and path-coefficient analysis indicated that maximum quantum yield (QY_max) is directly influencing the improvement of SSPY and reduction of grain DON accumulation, which is corroborated by principal component analysis. The chlorophyll fluorescence traits identified in the present investigation might be applied as a phenotyping tool for the large-scale identification of wheat sensitivity to FHB.

Growth and mortality of aerobic anoxygenic phototrophs in the North Pacific Subtropical Gyre.

Aerobic anoxygenic phototrophic (AAP) bacteria harvest light energy using bacteriochlorophyll-containing reaction centers to supplement their mostly heterotrophic metabolism. While their abundance and growth have been intensively studied in coastal environments, much less is known about their activity in oligotrophic open ocean regions. Therefore, we combined in situ sampling in the North Pacific Subtropical Gyre, north of O'ahu island, Hawaii, with two manipulation experiments. Infra-red epifluorescence microscopy documented that AAP bacteria represented approximately 2% of total bacteria in the euphotic zone with the maximum abundance in the upper 50 m. They conducted active photosynthetic electron transport with maximum rates up to 50 electrons per reaction center per second. The in situ decline of bacteriochlorophyll concentration over the daylight period, an estimate of loss rates due to predation, indicated that the AAP bacteria in the upper 50 m of the water column turned over at rates of 0.75-0.90 d-1. This corresponded well with the specific growth rate determined in dilution experiments where AAP bacteria grew at a rate 1.05 ± 0.09 d-1. An amendment of inorganic nitrogen to obtain N:P = 32 resulted in a more than 10 times increase in AAP abundance over 6 days. The presented data document that AAP bacteria are an active part of the bacterioplankton community in the oligotrophic North Pacific Subtropical Gyre and that their growth was mostly controlled by nitrogen availability and grazing pressure.IMPORTANCEMarine bacteria represent a complex assembly of species with different physiology, metabolism, and substrate preferences. We focus on a specific functional group of marine bacteria called aerobic anoxygenic phototrophs. These photoheterotrophic organisms require organic carbon substrates for growth, but they can also supplement their metabolic needs with light energy captured by bacteriochlorophyll. These bacteria have been intensively studied in coastal regions, but rather less is known about their distribution, growth, and mortality in the oligotrophic open ocean. Therefore, we conducted a suite of measurements in the North Pacific Subtropical Gyre to determine the distribution of these organisms in the water column and their growth and mortality rates. A nutrient amendment experiment showed that aerobic anoxygenic phototrophs were limited by inorganic nitrogen. Despite this, they grew more rapidly than average heterotrophic bacteria, but their growth was balanced by intense grazing pressure.

Mirrored transformation optics.

A mirrored transformation optics (MTO) approach is presented to overcome the material mismatch in transformation optics. It makes good use of the reflection behavior and introduces a mirrored medium to offset the phase discontinuities. Using this approach, a high-performance planar focusing lens of transmission type is designed, which has a larger concentration ratio than the other focusing lens obtained by the generalized Snell's law. The MTO will not change any functionality of the original lens and has promising potential applications in imaging and light energy harvesting.

Performance of Hydride Vapor Phase Epitaxy‐Grown GaInP Photovoltaics with Double‐Sided Al‐Containing Passivation Layers Under Air Mass 1.5 Global Solar Irradiation and Low‐Intensity Indoor Light Irradiation

High‐performance III–V photovoltaic devices have the potential for various applications; however, their high production cost represents a challenge for market expansion. Hydride vapor phase epitaxy (HVPE) is a fabrication technology that can reduce the epitaxial growth cost of III–V compound semiconductors. This study demonstrates the performances of HVPE‐grown GaInP photovoltaic devices for solar and indoor photovoltaic applications. Herein, HVPE‐grown GaInP photovoltaic devices with AlInP frontside and AlGaInP backside passivation layers are fabricated for the first time. The developed GaInP photovoltaic device measured under air mass 1.5 global solar spectrum illumination achieves an independently certified power conversion efficiency of 17.3%, which is a new record efficiency among HVPE‐grown GaInP single‐junction solar cells. Furthermore, the GaInP photovoltaic device grown using HVPE exhibits a high power conversion efficiency (34.7–37.1%) under an illumination of 500–2000 lux, respectively, emitted by a white light‐emitting diode. These results demonstrate that HVPE‐grown GaInP photovoltaic devices can be used in low‐intensity indoor light energy harvesting systems.

Innovative complex perovskites for efficient hydrogen Evolution: A DFT-Based design strategy

Recently, hydrogen, a high-energy, non-polluting fuel, has attracted considerable attention. Perovskites are of great interest in the hydrogen energy field due to their attractive properties. Herein, first-time novel complex perovskites [K(Mg+2Nb+5)O3] were designed computationally. The DFT has been utilized to systematically examine structural, electronic, optical, elastic, and mechanical properties to explore their potential applications in producing solar-driven hydrogen. Complex compositions (varying Mg+2 and Nb+5 concentrations) likely to adopt cubic or pseudocubic (a≈b≈c) perovskite structures based on structural parameters and the Goldschmidt tolerance factor. Including Nb in the crystal structure plays a significant role in shaping the band gap energy. Formation enthalpies show that all compounds are dynamically stable and synthesizable. Absorption coefficients (∼105cm-1) and effective optical responsiveness in UV and visible range make them a potential candidate for light energy harvesting. The computed high dielectric constant, a declining trend in refractive index and reflectivity, and minimum energy loss characteristics are attractive and are suitable for optoelectronic applications. Mechanical elements, ductility, anisotropy, toughness, and crack resistance proposed that compounds are highly desirable for various applications. The proposed complex compositions could catalyze efficient hydrogen evolution reactions (HERs) due to their suitable bandgap energies, suitable absorption coefficients, and alignment of the band edges regarding the redox potential of water.

Extending Infrared Emission via Energy Transfer in a CsPbI3-Cyanine Dye Hybrid.

Directing energy flow in light harvesting assemblies of nanocrystal-chromophore hybrid systems requires a better understanding of factors that dictate excited-state processes. In this study, we explore excited-state interactions within the CsPbI3-cyanine dye (IR125) hybrid assembly through a comprehensive set of steady-state and time-resolved absorption and photoluminescence (PL) experiments. Our photoluminescence investigations reveal the quenching of CsPbI3 emission alongside the simultaneous enhancement of IR125 fluorescence, providing evidence for a singlet energy transfer. The evaluation of both photoluminescence (PL) quenching and PL decay measurements yield ∼94% energy transfer efficiency for the CsPbI3-IR125 hybrid assembly. Transient absorption spectroscopy further unveils that this singlet energy transfer process operates on an ultrafast time scale, occurring within 400 ps with a rate constant of energy transfer of 1.4 × 1010 s-1. Our findings highlight the potential of the CsPbI3-IR125 hybrid assembly to extend the emission of halide perovskites into the infrared region, paving the way for light energy harvesting and display applications.

Symmetry breaking charge transfer leading to charge separation in a far-red absorbing bisstyryl-BODIPY dimer.

Symmetry breaking charge transfer is one of the important photo-events occurring in photosynthetic reaction centers that is responsible for initiating electron transfer leading to a long-lived charge-separated state and has been successfully employed in light-to-electricity converting optoelectronic devices. In the present study, we report a newly synthesized, far-red absorbing and emitting BODIPY-dimer to undergo symmetry-breaking charge transfer leading to charge-separated states of appreciable lifetimes in polar solvents. Compared to its monomer analog, both steady-state and time-resolved fluorescence originating from the S1 state of the dimer revealed quenching which increased with an increase in solvent polarity. The electrostatic potential map from DFT and the time-dependent DFT calculations suggested the existence of a quadrupolar type charge transfer state in polar solvents, and the singlet excited state to be involved in the charge separation process. The electrochemically determined redox gap being smaller than the energy of the S1 state supported the thermodynamic feasibility of the envisioned symmetry-breaking charge transfer and separation. The spectrum of the charge-separated state arrived from spectroelectrochemical studies, revealing diagnostic peaks helpful for transient spectral interpretation. Finally, ultrafast transient pump-probe spectroscopy provided conclusive evidence of diabatic charge separation in polar solvents by far-red pulsed laser light irradiation. The measured lifetime of the final charge-separated states was found to be 165 ps in dichlorobenzene, 140 ps in benzonitrile, and 43 ps in dimethyl sulfoxide, revealing their significance in light energy harvesting, especially from the less-explored far-red region.

Toward Indoor Simulations of OPV Cells for Visible Light Communication and Energy Harvesting

Toward Indoor Simulations of OPV Cells for Visible Light Communication and Energy Harvesting