Förster Resonance Energy Transfer in Luminescent Solar Concentrators

Fluorescence resonance energy transfer in atomically precise metal nanoclusters by cocrystallization-induced spatial confinement

Understanding the fluorescence resonance energy transfer (FRET) of metal nanoparticles at the atomic level has long been a challenge due to the lack of accurate systems with definite distance and orientation of molecules. Here we present the realization of achieving FRET between two atomically precise copper nanoclusters through cocrystallization-induced spatial confinement. In this study, we demonstrate the establishment of FRET in a cocrystallized Cu8(p-MBT)8(PPh3)4@Cu10(p-MBT)10(PPh3)4 system by exploiting the overlapping spectra between the excitation of the Cu10(p-MBT)10(PPh3)4 cluster and the emission of the Cu8(p-MBT)8(PPh3)4 cluster, combined with accurate control over the confined space between the two nanoclusters. Density functional theory is employed to provide deeper insights into the role of the distance and dipole orientations of molecules to illustrate the FRET procedure between two cluster molecules at the electronic structure level.

Boosting Excited-State Energy Transfer by Anchoring Dipole Orientation in Binary Thermally Activated Delayed Fluorescence/J-Aggregate Assemblies

Förster resonance energy transfer (FRET) has been widely applied in fluorescence imaging, sensing and so on, while developing useful strategy of boosting FRET efficiency becomes a key issue that limits the application. Except optimizing spectral properties, promoting orientation factor (κ2) has been well discussed but rarely utilized for boosting FRET. Herein, we constructed binary nano-assembling of two thermally activated delayed fluorescence (TADF) emitters (2CzPN and DMAC-DPS) with J-type aggregate of cyanine dye (C8S4) as doping films by taking advantage of their electrostatic interactions. Time-resolved spectroscopic measurements indicated that 2CzPN/Cy-J films exhibit an order of magnitude higher kFRET than DMAC-DPS/Cy-J films. Further quantitative analysing on kFRET and kDET indicated higher orientation factor (κ2) in 2CzPN/Cy-J films play a key role for achieving fast kFRET, which was subsequently confirmed by anisotropic measurements. Corresponding DFT/TDDFT calculation revealed strong "two-point" electrostatic anchoring in 2CzPN/Cy-J films that is responsible for highly orientated transitions. We provide a new strategy for boosting FRET in nano-assemblies, which might be inspired for designing FRET-based devices of sensing, imaging and information encryption.

Fluorescent antenna based on Förster resonance energy transfer (FRET) for optical wireless communications

The use of fluorescent antennas in optical wireless communications (OWC) has been demonstrated previously, and it has been shown that it is an efficient method for enhancing receiver performance, providing both signal gain and a wide field of view (FoV). To achieve a high concentration gain at the receiver output, the selected fluorophores should have a high photoluminescence quantum yield (PLQY), limited overlap between their absorption and emission spectra, and emit light that can be efficiently detected. In addition, to support a high modulation bandwidth, the photoluminescence (PL) lifetime of the fluorophore needs to be short. In this paper, we propose a new fluorescent antenna architecture based on Förster resonance energy transfer (FRET). Our results show that, due to the photophysical interactions between the energy donor and energy acceptor, the use of FRET simultaneously increases PLQY and reduces PL lifetime. Additionally, employing FRET leads to an increased Stokes shift, ensuring that the emitted light has longer wavelengths, thus reducing self-absorption. This shift can also increase the efficiency with which the fluorescence is detected by a typical silicon (Si) photodetector. Consequently, our OWC results show that a new FRET-based antenna can achieve a significantly higher concentration gain and a wider transmission bandwidth than a conventional non-FRET antenna, leading to much higher data rates.

Facile Tailoring of Metal-Organic Frameworks for Förster Resonance Energy Transfer-Driven Enhancement in Perovskite Photovoltaics

Förster resonance energy transfer (FRET) has demonstrated its potential to enhance the light energy utilization ratio of perovskite solar cells by interacting with metal-organic frameworks (MOFs) and perovskite layers. However, comprehensive investigations into how MOF design and synthesis impact FRET in perovskite systems are scarce. In this work, nanoscale HIAM-type Zr-MOF (HIAM-4023, HIAM-4024, and HIAM-4025) is meticulously tailored to evaluate FRET's existence and its influence on the perovskite photoactive layer. Through precise adjustments of amino groups and acceptor units in the organic linker, HIAM-MOFs are synthesized with the same topology, but distinct photoluminescence (PL) emission properties. Significant FRET is observed between HIAM-4023/HIAM-4024 and the perovskite, confirmed by spectral overlap, fluorescence lifetime decay, and calculated distances between HIAM-4023/HIAM-4024 and the perovskite. Conversely, the spectral overlap between the PL emission of HIAM-4025 and the perovskite's absorption spectrum is relatively minimal, impeding the energy transfer from HIAM-4025 to the perovskite. Therefore, the HIAM-4023/HIAM-4024-assisted perovskite devices exhibit enhanced EQE via FRET processes, whereas the HIAM-4025 demonstrates comparable EQE to the pristine. Ultimately, the HIAM-4023-assisted perovskite device achieves an enhanced power conversion efficiency (PCE) of 24.22% compared with pristine devices (PCE of 22.06%) and remarkable long-term stability under ambient conditions and continuous light illumination.

Semi-Transparent Luminescent Solar Concentrators Based on Intramolecular Energy Transfer in Polyurethane Matrices

Luminescent solar concentrators (LSCs) are spectral conversion devices offering interesting opportunities for the integration of photovoltaics into the built environment and portable systems. The Förster-resonance energy transfer (FRET) process can boost the optical response of LSCs by reducing energy losses typically associated to non-radiative processes occurring within the device under operation. In this work, a new class of FRET-based thin-film LSC devices is presented, in which the synthetic versatility of linear polyurethanes (PU) is exploited to control the photophysical properties and the device performance of the resulting LSCs. A series of luminescent linear PUs are synthesized in the presence of two novel bis-hydroxyl-functionalized luminophores of suitable optical properties, used as chain extenders during the step-growth polyaddition reaction for the formation of the linear macromolecular network. By synthetically tuning their composition, the obtained luminescent PUs can achieve a high energy transfer efficiency (≈90%) between the covalently linked luminophores. The corresponding LSC devices exhibit excellent photonic response, with external and internal photon efficiencies as high as ≈4% and ≈37%, respectively. Furthermore, their optimized power conversion efficiency combined with their enhanced average visible-light transmittance highlight their suitability for potential use as transparent solar energy devices.

Precise synthesis of BN embedded perylene diimide oligomers for fast-charging and long-life potassium-organic batteries

Replacing the C[double bond, length as m-dash]C bond with an isoelectronic BN unit is an effective strategy to tune the optoelectronic properties of polycyclic aromatic hydrocarbons (PAHs). However, precise control of the BN orientations in large PAH systems is still a synthetic challenge. Herein, we demonstrate a facile approach for the synthesis of BN embedded perylene diimide (PDI) nanoribbons, and the polarization orientations of the BN unit were precisely regulated in the two PDI trimers. These BN doped PDI oligomers show great potential as organic cathodes for potassium-ion batteries (PIBs). In particular, trans-PTCDI3BN exhibits great improvement in voltage potential, reversible capacities (ca. 130 mA h g-1), superior rate performance (19 s to 69% of the maximum capacity) and ultralong cyclic stability (nearly no capacity decay over 30 000 cycles), which are among those of state-of-the-art organic-based cathodes. Our synthetic approach stands as an effective way to access large PAHs with precisely controlled BN orientations, and the BN doping strategy provides useful insight into the development of organic electrode materials for secondary batteries.

A comprehensive dataset of photonic features on spectral converters for energy harvesting

Building integrated photovoltaics is a promising strategy for solar technology, in which luminescent solar concentrators (LSCs) stand out. Challenges include the development of materials for sunlight harvesting and conversion, which is an iterative optimization process with several steps: synthesis, processing, and structural and optical characterizations before considering the energy generation figures of merit that requires a prototype fabrication. Thus, simulation models provide a valuable, cost-effective, and time-efficient alternative to experimental implementations, enabling researchers to gain valuable insights for informed decisions. We conducted a literature review on LSCs over the past 47 years from the Web of ScienceTM Core Collection, including published research conducted by our research group, to gather the optical features and identify the material classes that contribute to the performance. The dataset can be further expanded systematically offering a valuable resource for decision-making tools for device design without extensive experimental measurements.

Covalently linked pyrene antennas for optically dense yet aggregation-resistant light-harvesting systems

In this study we present a novel energy transfer material inspired by natural light-harvesting antenna arrays, zinc(II) phthalocyanine-pyrene (ZnPcPy). The ZnPcPy system facilitates energy transfer from 16 covalently linked pyrene (Py) donor chromophores to the emissive central zinc(II) phthalocyanine (ZnPc) core. Nearly 98% energy transfer efficiency is determined from the changes in emission decay rates between free MePy to covalently linked Py, supported by comparisons of photoluminescence quantum yields using different excitation wavelengths. A comparative analysis of ZnPcPy and an equivalent mixture of ZnPc and MePy demonstrates the superior light-harvesting performance of the covalently linked system, with energy transfer rates 9705 times higher in the covalently bound system. This covalent strategy allows for very high loadings of absorbing Py chromophores to be achieved while also avoiding exciton quenching that would otherwise arise, with the same strategy widely applicable to other pairs of Főrster resonance energy transfer (FRET) chromophores.

An autonomous power temperature sensor based on window-integrated transparent PV using sustainable luminescent carbon dots

The energy efficiency of buildings can be significantly improved through the use of renewable energy sources. Luminescent solar concentrators (LSCs) appear to be a solution for integrating photovoltaic (PV) devices into the structure of buildings (windows, for instance) to enable low-voltage devices to be powered. Here, we present transparent planar and cylindrical LSCs based on carbon dots in an aqueous solution and dispersed in organic-inorganic hybrid matrices, which present photoluminescent quantum yield values up to 82%, facilitating an effective solar photon conversion. These LSCs showed the potencial for being incorporated as building windows due to an average light transmittance of up to ∼91% and color rendering index of up to 97, with optical and power conversion efficiency values of 5.4 ± 0.1% and 0.18 ± 0.01%, respectively. In addition, the fabricated devices showed temperature sensing ability enabling the fabrication of an autonomous power mobile temperature sensor. Two independent thermometric parameters were established based on the emission and the electrical power generated by the LSC-PV system, which could both be accessed by a mobile phone, enabling mobile optical sensing through multiparametric thermal reading with relative sensitivity values up to 1.0% °C^-1, making real-time mobile temperature sensing accessible to all users.

Efficient detection of L-aspartic acid and L-glutamic acid by self-assembled fluorescent microparticles with AIE and FRET activities

Amino acids play an important role in the formation of proteins, enzymes, hormones and peptides in animals. Moreover, aspartic acid and glutamic acid have a critical impact on the central nervous system as excitatory neurotransmitters. Here, we report the highly selective detection of L-glutamic acid (L-Glu) and L-aspartic acid (L-Asp) using fluorescent microparticles constructed by the combination of aggregation-induced emission and self-assembly-induced Förster resonance energy transfer.

Harvesting Triplet Excitons in High Mobility Emissive Organic Semiconductor for Efficiency Enhancement of Light-Emitting Transistors

Organic light-emitting transistors (OLETs), a kind of highly integrated and minimized optoelectronic device, demonstrate great potential applications in various fields. The construction of high-performance OLETs requires the integration of high charge carrier mobility, strong emission, and high triplet exciton utilization efficiency in the active layer. However, it remains a significant long-term challenge, especially for single component active layer OLETs. Herein, the successful harvesting of triplet excitons in a high mobility emissive molecule, 2,6-diphenylanthracene (DPA), through the triplet-triplet annihilation process is demonstrated. By incorporating a highly emissive guest into the DPA host system, an obvious increase in photoluminescence efficiency along with exciton utilization efficiency results in an obvious enhancement of external quantum efficiency of 7.2 times for OLETs compared to the non-doped devices. Moreover, well-tunable multi-color electroluminescence, especially white emission with Commission Internationale del'Eclairage  of (0.31, 0.35), from OLETs is also achieved by modulating the doping concentration with a controlled energy transfer process. This work opens a new avenue for integrating strong emission and efficient exciton utilization in high-mobility organic semiconductors for high-performance OLETs and advancing their related functional device applications.

High-efficiency liquid luminescent solar concentrator based on CsPbBr3 quantum dots

The performance degradation is still a challenge for the development of conventional polymer luminescent solar concentrator (LSC). Liquid LSC (L-LSC) may be an alternative due to polymerization-free fabrication. Here, we have prepared a CsPbBr₃ quantum dots (QDs)-based L-LSC by injecting the QDs solution into a self-assembly quartz glass mold. The as-fabricated L-LSC performance is evaluated by optical characterization and photo-electrical measurement. The external quantum efficiency of the L-LSC is up to 13.44%. After coupling the commercial solar cell, the optimal optical efficiency reaches 2.32%. These results demonstrate that L-LSC may provide a promising direction for advanced solar light harvesting technologies.