Donor-acceptor Pair Research Articles

Carbon-related donor–acceptor pair transition in the infrared in h-BN

Experimental studies of intentionally doped impurities for the understanding of conductivity control in hexagonal boron nitride (h-BN) ultrawide bandgap (UWBG) semiconductor are limited but are highly desired for emerging applications of h-BN. We report synthesis by hydride vapor phase epitaxy and comparison photoluminescence (PL) emission spectroscopy studies of intentionally carbon (C)-doped and undoped h-BN semi-bulk crystals. In addition to the well-known C-related emission lines observed previously, a C-impurity-related transition near 1.31 eV consisting of multiple phonon replicas has been observed in C-doped h-BN at room temperature. Phonon replicas involved in the 1.31 eV emission have been identified using polarization resolve PL spectroscopy as the transverse acoustic (TA)/longitudinal acoustic (LA) and out-of-plane optical phonon (ZO) modes at the middle point, T, between the Γ- and K-points in the first Brillouin zone. Based on the agreement between the spectral peak position of the observed dominant emission line at 1.31 eV and the calculated energy-level separation between CB donor (carbon replacing boron) and Ci acceptor (carbon interstitial), the observed IR emission line can be decisively assigned to the donor–acceptor pair (DAP) transition involving the CB donor and Ci acceptor assisted by the intervalley (Κ → Μ) scattering processes. The results reinforce the perception that C impurities form deep-level centers and provided an improved understanding of C impurities in h-BN.

Giant enhancement of fluorescence resonance energy transfer based on nanoporous gold with small amount of residual silver

Fluorescence resonance energy transfer (FRET) was found strongly enhanced by plasmon resonance. In this work, Nanoporous Gold with small amount of residual silver was used to form nanoporous gold/organic molecular layer compound with PSS and PAH. The ratio of its specific gold and silver content is achieved by controlling the time of its dealloying. Layered films of polyelectrolyte multilayers were assembled between the donor–acceptor pairs and NPG films to control distance. The maximum of FRET enhancement of 80-fold on the fluorescence intensity between the donor–acceptor pairs (CFP-YFP) is observed at a distance of ∼10.5 nm from the NPG film. This Nanoporous Gold with small amount of residual silver not only enhanced FRET 4-fold more than nanoporous gold of only gold content almost, but also effectively realized the regulation of FRET enhancement. The ability to precisely measure and regulate the enhancement of FRET enables the rational selection of plasmonic nanotransducer dimensions for the particular biosensing application.

Efficient Direct X-ray Detection and Imaging Based on a Lead-Free Electron Donor-Acceptor MOF.

Metal-organic frameworks (MOFs) have recently gained extensive attention as potential materials for direct radiation detection due to their strong radiation absorption, long-range order, and chemical tunability. However, it remains challenging to develop a practical MOF-based X-ray direct detector that possesses high X-ray detection efficiency, radiation stability, and environmental friendliness. The integration of donor-acceptor (D-A) pairs into crystalline MOFs is a powerful strategy for the precise fabrication of multifunctional materials with unique optoelectronic properties. Herein, a new lead-free MOF, Cu2I2(TPPA) (CuI-TPPA, TPPA = tris[4-(pyridine-4-yl)phenyl]amine), with a 6-fold interpenetrated structure is designed and synthesized based on the electron donor-acceptor strategy. CuI-TPPA has a large mobility-lifetime (μτ) product of 5.8 × 10-4 cm2 V-1 and a high detection sensitivity of 73.1 μC Gyair-1 cm-2, surpassing that of commercial α-Se detectors. Moreover, the detector remains fairly stable with only a 2% reduction in photocurrent under continuous bias irradiation conditions with a total dose of over 42.83 Gyair. The CuI-TPPA/poly(vinylidene fluoride) flexible composite X-ray detector films are successfully manufactured with different thicknesses. Through multifaceted assessments, the optimal thickness is found with a high detection sensitivity of up to 143.6 μC Gyair-1 cm-2. As proof-of-concept, 11 × 9 pixelated X-ray detectors are fabricated on the same composite film to realize X-ray direct imaging. This work opens up potential applications of MOFs in environmentally friendly and wearable devices for direct X-ray detection and imaging.

Single-Atom Catalysts on Covalent Organic Frameworks for Energy Applications.

Single-atom catalysts (SACs) have been investigated and applied to energy conversion devices. However, issues of metal agglomeration, low metal loading, and substrate stability have hindered realization of the SACs' full potential. Recently, covalent organic framework (COF)-based SACs have emerged as promising materials to enable highly efficient catalytic reactions. Here, we summarize the representative COF-based SACs and their wide application in clean energy devices and conversion reactions, such as hydrogen evolution reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, oxygen reduction reaction, and oxygen evolution reaction. Based on their catalysis conditions, these reactions are categorized into photocatalyzed and electrocatalyzed reactions. We also summarize their design strategies, including heteroatom inclusion, donor-acceptor pairs, pore engineering, interface engineering, etc. Although COF-based SACs are promising, more efforts, such as linkage engineering, functional groups, ionization, multifunctional sites for cocatalyzed systems, etc., could improve them to be the ideal SAC materials. At the end, we provide our perspectives on where the field will proceed in the next 5 years.

Visualization and correlation of drug release of risperidone/clozapine microspheres in vitro and in vivo based on FRET mechanism

This study addresses the challenging task of quantitatively investigating drug release from PLGA microspheres after in vivo administration. The objective is to employ Förster resonance energy transfer (FRET) to visualize drug-encapsulated microspheres in both in vitro and in vivo settings. The primary goal is to establish a quantitative correlation between FRET fluorescence changes and microsphere drug release. The study selects drugs with diverse structures and lipid solubility to explore release mechanisms, using PLGA as the matrix material. Clozapine and risperidone serve as model drugs. FRET molecules, Cy5 and Cy5.5, along with Cy7 derivatives, create FRET donor–acceptor pairs. In vitro results show that FRET fluorescence changes align closely with microsphere drug release, particularly for the Cy5.5-Cy7 pair. In vivo experiments involve subcutaneous administration of microspheres to rats, tracking FRET fluorescence changes while collecting blood samples. Pharmacokinetic studies on clozapine and risperidone reveal in vivo absorption fractions using the Loo-Riegelman method. Correlating FRET and in vivo absorption data establishes an in vitro–in vivo relationship (IVIVR). The study demonstrates that FRET-based fluorescence changes quantitatively link to microsphere drug release, offering an innovative method for visualizing and monitoring release in both in vitro and in vivo settings, potentially advancing clinical applications of such formulations.

Defects in layered boron nitride grown by Metal Organic Vapor Phase Epitaxy: luminescence and positron annihilation studies

Defects in two-dimensional boron nitride (BN) are candidates for a manifold of applications, for example, as single-photon emitters or optically addressable spin defects. However, the topic has proven to be complex and despite extensive research efforts, knowledge on midgap defects and their signature in photoluminescence (PL) remains fragmentary. Mass production of high-quality layered BN by Metal Organic Vapor Phase Epitaxy (MOVPE) is possible and effective, thus understanding the conditions of formation and identifying defects that arise in the material grown by this method is extremely important. Here, we present an analysis of the influence of the MOVPE growth conditions of layered BN on the occurrence of specific structural defects. PL spectra in the visible range were analysed involving the Huang-Rhys theory implemented in the fitting procedure for polycrystalline samples grown under various conditions. Such an approach allowed us to separate bands from individual entities. Two bands at 1.57 eV and 2.6 eV with phonon replicas were observed. The three additional bands are characterized by a broad emission centered at 1.38 eV, 1.9 eV and 2.24 eV. Further properties, including an analysis of the surface morphology, the impact of annealing and laser bleaching on the PL spectra and Positron Annihilation Spectroscopy (PAS) were considered to draw conclusions about the nature of the examined defects. The PAS analysis correlated with the PL of the BN layers allows us to classify the studied samples in terms of the concentrations of boron vacancies and their complexes. Based on the obtained results, we propose that the rich family of PL bands observed in various sp2-BN layers is associated with different defect complexes build of boron vacancies (VB), boron antisite defects (BN), substitutional carbon defects (CB, CN) and their donor-acceptor pairs. The main value of this paper is the transfer of knowledge gained about defects and the corresponding luminescent bands to characterize high-quality continuous epitaxial sp2-BN layers. The presented results constitute an important step toward the deterministic manipulation of defect concentrations in two-dimensional boron nitride, which opens up new pathways for future optoelectronic device application.

Nanometal Surface Energy Transfer (NSET) from Biologically Active Heterocyclic Ligands to Silver Nanoparticles Induces Enhanced Antimicrobial Activity against Gram-positive Bacteria

Herein we report the formation of a nanometal surface energy transfer (NSET) pair between a donor biologically active heterocyclic luminescent ligand such as 3-(1,3-Dioxoisoindolin-2-yl)-N, N-dimethylpropan-1-ammonium perchlorate (S4PNL; λem-408nm) and an acceptor silver nanoparticle (Ag NP; λabs-406nm). When the S4PNL ligand interacts with Ag NPs, the quenching in their luminescence intensity at 408nm is noticed, with a Stern-Volmer constant of 0.8×104 M-1. The present donor-acceptor pair displays a binding constant of 2.8×104 M-1 and binding sites of 1.12. The current work shows the energy transfer from a molecular dipole (S4PNL) to a nanometal surface (Ag NP) and thus follows the nanometal surface energy transfer (NSET) ruler with an energy transfer efficiency of 80.0%, 50% energy transfer efficiency distance (d0) of 4.9nm, donor-acceptor distance of 3.4nm. The alteration in the zeta potential value of S4PNL upon interaction with AgNP clearly demonstrates the strong electrostatic interaction between donor and acceptor. Importantly, the current NSET pair shows enhanced antimicrobial activity against gram-positive bacteria such as Bacillus cereus (B. cereus) in comparison to their parent components i.e. S4PNL ligand and Ag NP. The NSET pair shows maximum inhibition against B. cereus (9202.21±463.26 CFU/ml.) at 10% while minimum inhibition is observed at 0.01% of it (39,887.19±242.67 CFU/ml.).

Exciton Transfer Between Extended Electronic States in Conjugated Inter-Polyelectrolyte Complexes.

Artificial light harvesting, a process that involves converting sunlight into chemical potential energy, is considered to be a promising part of the overall solution to address urgent global energy challenges. Conjugated polyelectrolyte complexes (CPECs) are particularly attractive for this purpose due to their extended electronic states, tunable assembly thermodynamics, and sensitivity to their local environment. Importantly, ionically assembled complexes of conjugated polyelectrolytes can act as efficient donor-acceptor pairs for electronic energy transfer (EET). However, to be of use in material applications, we must understand how modifying the chemical structure of the CPE backbone alters the EET rate beyond spectral overlap considerations. In this report we investigate the dependence of the EET efficiency and rate on the electronic structure and excitonic wave function of the CPE backbone. To do so, we synthesized a series of alternating copolymers where the electronic states are systematically altered by introducing comonomers with electron withdrawing and electron-rich character while keeping the linear ionic charge density nearly fixed. We find evidence that the excitonic coupling may be significantly affected by the exciton delocalization radius, in accordance with analytical models based on the line-dipole approximation and quantum chemistry calculations. Our results imply that care should be taken when selecting CPE components for optimal CPEC EET. These results have implications for using CPECs as key components in water-based light-harvesting materials, either as standalone assemblies or as adsorbates on nanoparticles and thin films.

Zinc selenide quantum dots as fluorescent labels for biomedical imaging

We, herein, report a facile green synthetic route for the gram‐scale synthesis of high‐quality thiol‐derivatized zinc selenide quantum dots (QDs) using selenourea as the source of selenium at a relatively low temperature. The one‐pot synthesis of colloidal dots has been achieved by selenizing zinc (II) acetate in a non‐coordinating solvent medium. The structural, microstructural, optical, thermal, textural and electronic properties of the as‐synthesized monodisperse ZnSe dots have been investigated in detail. We attribute the observed green emission from the dots to the donor‐acceptor pair (DAP) recombination of photoexcited charge carriers. All the findings of the investigation indicate that ZnSe QDs hold great promise as a nanoscale emissive probe to unveil cellular dynamics beyond the capabilities of conventional imaging techniques.

Yolk-shell nanospheres based silane-functionalized carbon dots: Designed synthesis and application in highly selective determination of aflatoxin biosynthesis-related genes nor-1 in cereal crops

This study presented advanced monitoring approaches for the aflatoxin gene cluster in Aspergillus flavus and Aspergillus parasiticus, which are effective tools for controlling aflatoxin proliferation in the food chain. A novel approach involved a ratiometric fluorescence probe based on yolk-shell nanospheres (bCDs@SiO2@gQDs). The probe's fluorescence was activated by DNA hybridization with the modified bCDs@SiO2@gQDs and gold nanoparticles (AuNPs), functioning through donor–acceptor pairs. The exceptional properties of the gQDs and the high FRET efficiency of this system established a functionalized platform for DNA labeling. When the nor-1 gene was present, FRET between the gQDs and AuNPs triggered fluorescence quenching, enabling nor-1 gene detection. The yolk-shell nanostructure of the fluorescent nanoprobes provided an internal reference, reducing experimental errors due to background noise, instrumentation factors, and probe concentration. This allowed for accurate and highly sensitive quantitative determination of the nor-1 gene. The ratiometric fluorescence assay demonstrated a broad linear range (0.1–100 nM) and a low detection limit (12.83 pM) for the nor-1 gene. Tests on non-contaminated maize samples spiked with various concentrations of the nor-1 gene achieved recovery rates between 95.43 % and 101.46 %. This biosensor represents a significant advancement in food safety, offering a simple, rapid, and sensitive method for monitoring agricultural products.

Temperature Dependent Photoluminescence Spectra of Nanocrystalline Zinc Oxide: Effect of processing condition on the excitonic and defect mediated emissions

Nanocrystalline zinc oxide (ZnO) with crystallite size in the range 85 -89 nm are prepared by the thermal decomposition of carbonate precursor under three different atmospheres, viz., in air ambiance, under nitrogen flow, and in vacuum. O 1s X-ray photoelectron spectra indicate that the atomic percentage of oxygen vacancies is more in the sample prepared under vacuum while adsorbed oxygen is more in the sample prepared in air ambience. Optical band gaps for the samples are in the range 3.17–3.20 eV. Room temperature photoluminescence spectra of the samples reveal band edge emission in the UV range (⁓3.18 eV) and broad defect mediated visible emission (⁓1.60–2.70 eV). Emission profile of excitonic emission at 80 K can be resolved into two free excitonic peaks at 3.42 eV (FX-A) and 3.46 eV (FX-B), donor bound excitonic peaks (D0X), peak due to transition of free electrons to acceptor levels (FA) donor-acceptor pair (DAP) emission and phonon replicas. D0X peak at ⁓3.35 eV has contribution from oxygen vacancies (Vo) and Zn interstitials (Zni). The most intense peak in the case of all the three samples is the FA peak at ⁓ 3.31 eV which has contribution from zinc vacancies (VZn). Temperature dependent variation of the dominant D0X and FA peaks in the range 80–400 K are analyzed using modified Varshni model which considers contributions from electron-phonon scattering and lattice thermal expansion. Defect dependent emission intensity is maximum at 80 K due to freeze-out of phonons and decreases with increase in temperature. The evolution of the colour of luminescence with temperature is studied using CIE plot method.

Donor-acceptor pairs in wide-bandgap semiconductors for quantum technology applications

We propose a quantum science platform utilizing the dipole-dipole coupling between donor-acceptor pairs (DAPs) in wide bandgap semiconductors to realize optically controllable, long-range interactions between defects in the solid state. We carry out calculations based on density functional theory (DFT) to investigate the electronic structure and interactions of DAPs formed by various substitutional point-defects in diamond and silicon carbide (SiC). We determine the most stable charge states and evaluate zero phonon lines using constrained DFT and compare our results with those of simple donor-acceptor pair (DAP) models. We show that polarization differences between ground and excited states lead to unusually large electric dipole moments for several DAPs in diamond and SiC. We predict photoluminescence spectra for selected substitutional atoms and show that while B-N pairs in diamond are challenging to control due to their large electron-phonon coupling, DAPs in SiC, especially Al-N pairs, are suitable candidates to realize long-range optically controllable interactions.

Bridgman-Grown (Cd,Mn)Te and (Cd,Mn)(Te,Se): A Comparison of Suitability for X and Gamma Detectors.

This study explores the suitability of (Cd,Mn)Te and (Cd,Mn)(Te,Se) as room-temperature X-ray and gamma-ray detector materials, grown using the Bridgman method. The investigation compares their crystal structure, mechanical and optical properties, and radiation detection capabilities. Both crystals can yield large-area single crystal samples measuring approximately 30 × 30 mm2. In low-temperature photoluminescence analysis, both materials showed defect states, and annealing in cadmium vapors effectively eliminated donor-acceptor pair luminescence in (Cd,Mn)Te but not in (Cd,Mn)(Te,Se). Moreover, harder (Cd,Mn)(Te,Se) exhibited a higher etch pit density compared to softer (Cd,Mn)Te. X-ray diffraction examination revealed uniform lattice constant distribution in both compounds, with variations at a part per million level. (Cd,Mn)Te crystals demonstrated excellent single crystal properties with narrower omega scan widths, while (Cd,Mn)(Te,Se) exhibited a high contribution of block-like structures with significantly larger misorientation angles. Spectroscopic evaluations revealed better performance of a pixelated (Cd,Mn)Te detector, in comparison to (Cd,Mn)(Te,Se), achieving a mean full width at half maximum of 14% for the 122 keV gamma peak of Co-57. The reduced performance of the (Cd,Mn)(Te,Se) detector may be attributed to deep trap-related luminescence or block-like structures with larger misorientation angles. In conclusion, Bridgman-grown (Cd,Mn)Te emerges as a more promising material for X-ray and gamma-ray detectors when compared to (Cd,Mn)(Te,Se).

Photoluminescence from FRET pairs coupled with Mie-resonant silicon nanospheres.

Optically resonant nanoparticles decorated with donor-acceptor molecular pairs have been attracting attention for applications as nanoprobes in bioimaging and biosensing. We produced composite nanoparticles composed of donor-acceptor molecular pairs and silicon nanospheres (Si NSs) with diameters of 100-200 nm exhibiting Mie resonances in the visible range and studied the effect of Mie resonances on their photoluminescence properties. We showed that the photoluminescence spectra are strongly modified by Mie resonances and the spectral shape is controlled in a wide range by the Si NS size; by controlling the size, we can achieve the photoluminescence maximum from that of a donor molecule to that of an acceptor molecule almost continuously. From the photoluminescence decay properties in combination with theoretical calculations, we showed that the observed strong modification of the spectral shape is mainly due to the Purcell effect on donor and acceptor molecules, and the effect of Mie resonances on the Förster resonance energy transfer (FRET) rate is relatively small. We also showed that because of the large Purcell effect and the small FRET rate enhancement, Mie resonances decrease the FRET efficiency.

Design and virtual screening of donor and non-fullerene acceptor for organic solar cells using long short-term memory model

In this study, we trained long short-term memory models to predict photovoltaic performance parameters. Additionally, we cleaved and reorganized molecules to obtain novel high-performance donor–acceptor pairs.

Control of excitation selectivity in pulse EPR on spin-correlated radical pairs with shaped pulses.

Spin-correlated radical pairs generated by photoinduced electron transfer are characterised by a distinctive spin polarisation and a unique behaviour in pulse electron paramagnetic resonance (EPR) spectroscopy. Under non-selective excitation, an out-of-phase echo signal modulated by the dipolar and exchange coupling interactions characterising the radical pair is observed and allows extraction of geometric information in the two-pulse out-of-phase electron spin echo envelope modulation (ESEEM) experiment. The investigation of the role of spin-correlated radical pairs in a variety of biological processes and in the fundamental mechanisms underlying device function in optoelectronics, as well as their potential use in quantum information science, relies on the ability to precisely address and manipulate the spins using microwave pulses. Here, we explore the use of shaped pulses for controlled narrowband selective and broadband non-selective excitation of spin-correlated radical pairs in two model donor-bridge-acceptor triads, characterised by different spectral widths, at X- and Q-band frequencies. We demonstrate selective excitation with close to rectangular excitation profiles using BURP (band-selective, uniform response, pure-phase) pulses and complete non-selective excitation of both spins of the radical pair using frequency-swept chirp pulses. The use of frequency-swept pulses in out-of-phase ESEEM experiments enables increased modulation depths and, combined with echo transient detection and Fourier transformation, correlation of the dipolar frequencies with the EPR spectrum and therefore the potential to extract additional information on the donor-acceptor pair geometry.

AgInS2-Embedded Photocatalytic Membrane: Insights into the Excited State and Electron Transfer Dynamics.

Photocatalytic reactions at semiconductor nanocrystal surfaces are useful for synthesizing value-added chemicals using sunlight. Semiconductor nanocrystals dispersed in a rigid framework, such as polymer film, can mitigate issues such as aggregation, product separation, and other challenges that are usually encountered in suspensions or slurries. Using a cation exchange technique, we successfully embedded AgInS2 nanoparticles into a Nafion matrix, termed AgInS2-Nafion. This was achieved through a galvanic exchange between In and Ag in In2S3 present within the Nafion film, enabling an adjustable Ag:In ratio for optimized photophysical properties. As in the case of colloidal suspension, the AgInS2 particles embedded in Nafion exhibit a long absorption tail, a broad emission band with a large Stokes shift, and emission lifetimes extending into the microseconds that are characteristic of donor-acceptor pairs, DAP. Remediation of surface states with the treatment of 3-mercaptopropionic acid resulted in significant enhancement in the emission yield. Charge carrier generation through bandgap excitation as well as activation of DAP states which reside within the bandgap is probed through transient absorption spectroscopy. The photocatalytic activity of AgInS2-Nafion was probed by using thionine as an electron acceptor. The electron transfer rate constant from excited AgInS2 to thionine as observed from transient absorption spectroscopy was determined to be ∼6.3 × 1010 s-1. The design of a photoactive membrane offers new ways to carry out photocatalytic processes with greater selectivity.

Curving the solvatochromic tendency of pyridinium phenolate sensors by increasing their sensitivity to solvent polarizability

Three classic pyridinium-phenolate sensors exhibiting negative solvatochromism were modified by the addition of a 1,4-phenylene linker, resulting in three derivatives displaying inverted solvatochromism, with inversion points observed in polar solvents, such as DMSO. This study shows that the 1,4-phenylene linker is essential for the inverted solvatochromism of this sensor class. DFT calculations, multiparametric regressions, and molecular dynamics simulations in methanol suggest that the inversion is caused by increased sensitivity to the polarizability of the solvent and the loss of hydrogen bonds in solution. Finally, the present series presents a method for transforming negative solvatochromic pyridinium-phenolates into sensors displaying inverted solvatochromism by adding the 1,4-phenylene unit to the π-linker between the donor-acceptor pair.

NATURE OF ZINC OXIDE COLLOIDAL NANOCRYSTALS PHOTOLUMINESCENCE

The purpose of the study is to determine the nature of the radiative transitions responsible for the visible radiation of zinc oxide nanocrystals. Show that the size of nanocrystallites does not affect the spectral composition and location of long-wave luminescence. ZnO nanocrystals obtained by the method of colloidal synthesis with or without gelatin stabilization were investigated in the paper. The size of the nanocrystallites was determined in the approximation of the effective masses by the magnitude of the fundamental absorption edge shift. The results of calculating the size of nanocrystallites agree well with the results of SEM studies. It is shown that the main factor affecting the size of nanocrystallites is the concentration of precursors. Photoluminescence spectra of colloidal ZnO nanocrystals were studied in two spectral regions – ultraviolet and visible. Photoluminescence spectra in the ultraviolet region are characterized by three emission lines, the location of which depends on the concentration of precursors, that is, on the width of the band gap. Analysis of the energy states of intrinsic defects in nanostructured zinc oxide showed that the first two emission lines are associated with radiative transitions of excitons bound on neutral interstitial zinc atoms and on neutral zinc vacancies. The third line of ultraviolet radiation is caused by radiative transitions with the participation of deep donors, which are interstitial zinc atoms in the +2 charge state. The visible radiation spectra of colloidal ZnO nanocrystals are characterized by broad non-elemental emission bands in the blue-green and yellow-red regions of the spectrum. A detailed analysis of the spectra at different concentrations of precursors showed that the change in concentrations of precursors does not affect the spectral location of elementary emission lines. The absence of impurity absorption lines indicates that the centers responsible for visible radiation are donor-acceptor pairs. The analysis of the ratio of the emission lines intensities with increasing concentrations of the precursors shows that interstitial zinc and oxygen atoms dominate in the studied nanocrystals at high concentrations. As a result, in samples with a high concentration of precursors, blue radiation dominates over yellow and green. Thus, the study shows that by changing the concentrations of precursors, it is possible to influence both the spectral location of the edge ultraviolet luminescence and the intensity of individual long-wave luminescence components. The resulting colloidal ZnO nanocrystals can be used as luminescent sensors.

Achieving High External Quantum Efficiency for ITIC‐Based Organic Solar Cells with Negligible Homo Energy Offsets

AbstractMinimizing energy loss in organic solar cells (OSCS) is critical for attaining high photovoltaic performance. Among the parameters that correlated to photovoltaic performance, the energy offsets between donor–acceptor pairs play a vital role in photoelectric conversion processes. For so far reported a large number of non‐fullerene acceptors (NFAs), only Y6 and its derivatives can achieve external quantum efficiencies (EQEs) over 80% with negligible energy offsets when combined with polymeric donors. Thus, understanding the relationship between energy offsets and energy losses in representative NFAs is the key to further enhancing the efficiency of OSCs. In this study, a series of wide‐bandgap polymer donors based on pyrrolo[3,4‐f]benzotriazole‐5,7(6H)‐dione (TzBI) and benzo[1,2‐c:4,5‐c′] dithiophene‐4,8‐dione building blocks are combined with representative NFAs, including ITIC and Y6, to gain deep insights into their photovoltaic performances and related energy losses. Outstanding EQEs (≈70%) and suppressed non‐radiative recombination are achieved at negligible energy offsets. Moreover, it is noted that a prolonged exciton lifetime of acceptor is not essential to obtain high EQEs in OSCs with negligible energy offsets. Eventually, ITIC derivatives with high electroluminescence efficiencies and near‐infrared absorptions have the potential to be assembled to obtain high‐efficiency OSCs.