Radiative cooling and indoor light management enabled by a transparent and self-cleaning polymer-based metamaterial.

Transparent roofs and walls offer a compelling solution for harnessing natural light. However, traditional glass roofs and walls face challenges such as glare, privacy concerns, and overheating issues. In this study, we present a polymer-based micro-photonic multi-functional metamaterial. The metamaterial diffuses 73% of incident sunlight, creating a more comfortable and private indoor environment. The visible spectral transmittance of the metamaterial (95%) surpasses that of traditional glass (91%). Furthermore, the metamaterial is estimated to enhance photosynthesis efficiency by ~9% compared to glass roofs. With a high emissivity (~0.98) close to that of a mid-infrared black body, the metamaterial is estimated to have a cooling capacity of ~97 W/m2 at ambient temperature. The metamaterial was about 6 °C cooler than the ambient temperature in humid Karlsruhe. The metamaterial exhibits superhydrophobic performance with a contact angle of 152°, significantly higher than that of glass (26°), thus potentially having excellent self-cleaning properties.

Determining Structures of Layer-by-Layer Spin-Coated Zinc Dicarboxylate-Based Metal-Organic Thin Films.

Thin films of crystalline solids with substantial free volume from organic chromophores and metal secondary building units (SBUs) are promising for engineering new optoelectronic properties through control of interchromophore coupling. Zn-based SBUs are especially relevant in this case because they avoid quenching the chromophore's luminescence. We find that layer-by-layer spin-coating using Zn acetate dihydrate and benzene-1,4-dicarboxylic acid (H2BDC) and biphenyl-4,4'-dicarboxylic acid (H2BPDC) linkers easily produces crystalline thin films. However, analysis of the grazing-incidence wide-angle X-ray scattering (GIWAXS) data reveals the structures of these films vary significantly with the linker, and metal-to-linker molar ratio used for fabrication. Under equimolar conditions, H2BPDC creates a type of structure like that proposed for SURMOF-2, whereas H2BDC generates a different metal-hydroxide-organic framework. Large excess of Zn2+ ions causes the growth of layered zinc hydroxides, irrespective of the linker used. Density functional theory (DFT) calculations provide structural models with minimum total energy that are consistent with the experimentally observed diffractograms. In the broader sense, this work illustrates the importance in this field of careful structural determination, e.g., by utilizing GIWAXS and DFT simulations to determine the structure of the obtained crystalline metal-organic thin films, so properties can be rationally engineered and explained.

High Quantum Yield Shortwave Infrared Luminescent Tracers for Improved Sorting of Plastic Waste.

More complete recycling of plastic waste is possible only if new technologies that go beyond state-of-the-art near-infrared (NIR) sorting are developed. For example, tracer-based sorting is a new technology that explores the upconversion or down-shift luminescence of special tracers based on inorganic materials codoped with lanthanide ions. Specifically, down-shift tracers emit in the shortwave infrared (SWIR) spectral range and can be detected using a SWIR camera preinstalled in a state-of-the-art sorting machine for NIR sorting. In this study, we synthesized a very efficient SWIR tracer by codoping Li3Ba2Gd3 (MoO4)8 with Yb3+ and Er3+, where Yb3+ is a synthesizer ion (excited near 976 nm) and Er3+ emits near 1550 nm. Fine-tuning of the doping concentration resulted in a tracer (Li3Ba2Gd(3-x-y)(MoO4)8:xYb3+, yEr3+, where x = 0.2 and y = 0.4) with a high photoluminescence quantum yield for 1550 nm emission of 70% (using 976 nm excitation). This tracer was used to mark plastic objects. When the object was illuminated by a halogen lamp and a 976 nm laser, the three parts could be easily distinguished based on reflectance and luminescence spectra in the SWIR range: a plastic bottle made of polyethylene terephthalate, a bottle cap made of high-density polyethylene, and a label made of the tracer Li3Ba2Gd3(MoO4)8:Yb3+, Er3+. Importantly, the use of the tracer in sorting may require only the installation of a 976 nm laser in a state-of-the-art NIR sorting system.

Solar-pumped fiber laser using a solid-state luminescent solar collector.

We have developed a fully planar solar-pumped fiber laser using a solid-state luminescent solar collector (LSC). This laser does not use any focusing device, such as a lens or mirror; thus, it can lase without tracking the sun. Our developed device with an aperture of 30 cm emits 15 mW, corresponding to an optical-to-optical conversion efficiency of 0.023% and a collection efficiency of 0.21 W/m2. A 12-fold improvement over a previously developed liquid LSC is achieved by combining the total internal reflection of the solid-state LSC with dielectric multilayer mirrors. The observed laser power is in good agreement with that predicted via numerical simulation, demonstrating the effectiveness of our proposed method.

Structure and luminescence properties of Dy3+ doped quaternary tungstate Li3Ba2Gd3(WO4)8 for application in wLEDs.

Quaternary tungstates with the composition Li3Ba2Gd3(WO4)8 doped with different concentrations of Dy3+ (from 0.5 to 10 at%) were prepared by the solid-state reaction method at 900 °C. Their structural, spectroscopic and optical properties were studied systematically in this work. X-ray diffraction analysis confirmed the crystallization of Li3Ba2Gd3(WO4)8 to have a monoclinic structure (sp. gr. C2/c); the lattice constants for 1 at% doping concentration of Dy3+ are a = 5.2126(2) Å, b = 12.7382(1) Å, c = 19.1884(3) Å, Vcalc = 1273,40(4) Å3 and ß = a × c = 91.890(9)°. The first principles calculations for the undoped crystal revealed a direct bandgap of 2.45 eV, which is very close to the experimental one. The identified broad, and strong excitation peak at 450 nm indicates that Li3Ba2Gd3(WO4)8:Dy3+ phosphors are suitable to be pumped by a blue laser diode (LD). Under excitation at 445 nm, the phosphor showed a stronger luminescence peak at 575 nm which corresponds to the Dy3+:4F9/2 → 6H13/2 transition, and three weaker emissions peaks at 477, 661, and 750 nm. Meanwhile, the effect of different Dy3+ contents on the luminescence properties was investigated. The optimum concentration to minimize the quenching effect was 4 at% and the critical distance is 31.209 Å. The phosphor emitted strong greenish-yellow light situated at (0.425, 0.472) in CIE coordinates with a color temperature of 3652 K. All the measured luminescence lifetime curves exhibited a single-exponential nature. Excellent thermal stability was found for this tungstate phosphor (the activation energy is 0.352 ± 0.01 eV). The measured absolute photoluminescence quantum yield was around 10.5%. The results presented in this work show that Li3Ba2Gd3(WO4)8:Dy3+ phosphors with strong yellow emission are promising candidates for white-light emitting LED (wLED) applications.

Preventing cation intermixing enables 50% quantum yield in sub-15 nm short-wave infrared-emitting rare-earth based core-shell nanocrystals.

Short-wave infrared (SWIR) fluorescence could become the new gold standard in optical imaging for biomedical applications due to important advantages such as lack of autofluorescence, weak photon absorption by blood and tissues, and reduced photon scattering coefficient. Therefore, contrary to the visible and NIR regions, tissues become translucent in the SWIR region. Nevertheless, the lack of bright and biocompatible probes is a key challenge that must be overcome to unlock the full potential of SWIR fluorescence. Although rare-earth-based core-shell nanocrystals appeared as promising SWIR probes, they suffer from limited photoluminescence quantum yield (PLQY). The lack of control over the atomic scale organization of such complex materials is one of the main barriers limiting their optical performance. Here, the growth of either homogeneous (α-NaYF4) or heterogeneous (CaF2) shell domains on optically-active α-NaYF4:Yb:Er (with and without Ce3+ co-doping) core nanocrystals is reported. The atomic scale organization can be controlled by preventing cation intermixing only in heterogeneous core-shell nanocrystals with a dramatic impact on the PLQY. The latter reached 50% at 60 mW/cm2; one of the highest reported PLQY values for sub-15 nm nanocrystals. The most efficient nanocrystals were utilized for in vivo imaging above 1450 nm.

Absolute quantum yield for understanding upconversion and downshift luminescence in PbF2:Er3+,Yb3+ crystals.

The search for new materials capable of efficient upconversion continues to attract attention. In this work, a comprehensive study of the upconversion luminescence in PbF2:Er3+,Yb3+ crystals with different concentrations of Yb3+ ions in the range of 2 to 7.5 mol% (Er3+ concentration was fixed at 2 mol%) was carried out. The highest value of upconversion quantum yield (ϕUC) 5.9% (at 350 W cm-2) was found in the PbF2 crystal doped with 2 mol% Er3+ and 3 mol% Yb3+. Since it is not always easy to directly measure ϕUC and estimate the related key figure of merit parameter, saturated photoluminescence quantum yield (ϕUCsat), a method to reliably predict ϕUCsat can be useful. Judd-Ofelt theory provides a convenient way to determine the radiative lifetimes of the excited states of rare-earth ions based on absorption measurements. When the luminescence decay times after direct excitation of a level are also measured, ϕUCsat for that level can be calculated. This approach is tested on a series of PbF2:Er3+,Yb3+ crystals. Good agreement between the estimates obtained as above and the directly experimentally measured ϕUCsat values is demonstrated. In addition, three methods of Judd-Ofelt calculations on powder samples were tested and the results were compared with Judd-Ofelt calculations on single crystals, which served as the source of the powder samples. Taken together, the results presented in our work for PbF2:Er3+,Yb3+ crystals contribute to a better understanding of the UC phenomena and provide a reference data set for the use of UC materials in practical applications.

Limitation of room temperature phosphorescence efficiency in metal organic frameworks due to triplet-triplet annihilation.

The effect of triplet-triplet annihilation (TTA) on the room-temperature phosphorescence (RTP) in metal-organic frameworks (MOFs) is studied in benchmark RTP MOFs based on Zn metal centers and isophthalic or terephthalic acid linkers (ZnIPA and ZnTPA). The ratio of RTP to singlet fluorescence is observed to decrease with increasing excitation power density. Explicitly, in ZnIPA the ratio of the RTP to fluorescence is 0.58 at 1.04 mW cm-2, but only 0.42 at (the still modest) 52.6 mW cm-2. The decrease in ratio is due to the reduction of RTP efficiency at higher excitation due to TTA. The density of triplet states increases at higher excitation power densities, allowing triplets to diffuse far enough during their long lifetime to meet another triplet and annihilate. On the other hand, the shorter-lived singlet species can never meet an annihilate. Therefore, the singlet fluorescence scales linearly with excitation power density whereas the RTP scales sub-linearly. Equivalently, the efficiency of fluorescence is unaffected by excitation power density but the efficiency of RTP is significantly reduced at higher excitation power density due to TTA. Interestingly, in time-resolved measurements, the fraction of fast decay increases but the lifetime of long tail of the RTP remains unaffected by excitation power density. This may be due to the confinement of triplets to individual grains, leading decay to be faster until there is only one triplet per grain left. Subsequently, the remaining "lone triplets" decay with the unchanging rate expressed by the long tail. These results increase the understanding of RTP in MOFs by explicitly showing the importance of TTA in determining the (excitation power density dependent) efficiency of RTP. Also, for applications in optical sensing, these results suggest that a method based on long tail lifetime of the RTP is preferable to a ratiometric approach as the former will not be affected by variation in excitation power density whereas the latter will be.

Dual-color dynamic anti-counterfeiting labels with persistent emission after visible excitation allowing smartphone authentication.

A significant impediment to the deployment of anti-counterfeiting technologies is the reliance on specialized hardware. Here, anti-counterfeiting labels are developed that are both excited and detected using a smartphone. The persistent luminescence pattern and color changes on the timescale of hundreds of milliseconds to seconds. The labels can be authenticated by comparing still images from the red and green channels of video acquired at known times after flashlight excitation against expected reference patterns. The labels are based on a green-emitting SrAl2O4: Eu2+,Dy3+ (SAED), and red-emitting CaS:Eu2+ phosphors whose lifetimes are varied: (i) for SAED from 0.5 to 11.7 s by annealing the commercial material in air; and (ii) CaS:Eu2+ from 0.1 to 0.6 s by varying the dopant concentration. Examples of anti-counterfeiting labels exhibiting changing emission patterns and colors on a seven-segment display, barcode, and emoji are demonstrated. These results demonstrate that phosphors with visible absorption and tunable persistent luminescence lifetimes on the order of hundreds of milliseconds to seconds are attractive for anti-counterfeiting applications as they allow authentication to be performed using only a smartphone. Further development should allow richer color shifts and enhancement of security by embedding further covert anti-counterfeiting features.

Drying and Coating of Perovskite Thin Films: How to Control the Thin Film Morphology in Scalable Dynamic Coating Systems.

Hybrid perovskite photovoltaics combine high performance with the ease of solution processing. However, to date, a poor understanding of morphology formation in coated perovskite precursor thin films casts doubt on the feasibility of scaling-up laboratory-scale solution processes. Oblique slot jet drying is a widely used scalable method to induce fast crystallization in perovskite thin films, but deep knowledge and explicit guidance on how to control this dynamic method are missing. In response, we present a quantitative model of the drying dynamics under oblique slot jets. Using this model, we identify a simple criterion for successful scaling of perovskite solution printing and predict coating windows in terms of air velocity and web speed for reproducible fabrication of perovskite solar cells of ∼15% in power conversion efficiency─in direct correlation with the morphology of fabricated thin films. These findings are a corner stone toward scaling perovskite fabrication from simple principles instead of trial and error optimization.

Cubic versus hexagonal - phase, size and morphology effects on the photoluminescence quantum yield of NaGdF4:Er3+/Yb3+ upconverting nanoparticles.

Upconverting nanoparticles (UCNPs) are well-known for their capacity to convert near-infrared light into UV/visible light, benefitting various applications where light triggering is required. At the nanoscale, loss of luminescence intensity is observed and thus, a decrease in photoluminescence quantum yield (PLQY), usually ascribed to surface quenching. We evaluate this by measuring the PLQY of NaGdF4:Er3+,Yb3+ UCNPs as a function of size (ca. 15 to 100 nm) and shape (spheres, cubes, hexagons). Our results show that the PLQY of α-phase NaGdF4 Er3+,Yb3+ surpasses that of ß-NaGdF4 for sizes below 20 nm, an observation related to distortion of the crystal lattice when the UCNPs become smaller. The present study also underlines that particle shape must not be neglected as a relevant parameter for PLQY. In fact, based on a mathematical nucleus/hull volumetric model, shape was found to be particularly relevant in the 20 to 60 nm size range of the investigated UCNPs.

BODIPY-pyrene donor-acceptor sensitizers for triplet-triplet annihilation upconversion: the impact of the BODIPY-core on upconversion efficiency.

Triplet-triplet annihilation upconversion (TTA-UC) is an important type of optical process with applications in biophotonics, solar energy harvesting and photochemistry. In most of the TTA-UC systems, the formation of triplet excited states takes place via spin-orbital interactions promoted by heavy atoms. Given the crucial role of heavy atoms (especially noble metals, such as Pd and Pt) in promoting intersystem crossing (ISC) and, therefore, in production of UC luminescence, the feasibility of using more readily available and inexpensive sensitizers without heavy atoms remains a challenge. Here, we investigated sensitization of TTA-UC using BODIPY-pyrene heavy-atom-free donor-acceptor dyads with different numbers of alkyl groups in the BODIPY scaffold. The molecules with four and six alkyl groups are unable to sensitize TTA-UC in the investigated solvents (tetrahydrofuran (THF) and dichloromethane (DCM)) due to negligible ISC. In contrast, the dyad with two methyl groups in the BODIPY scaffold and the dyad with unsubstituted BODIPY demonstrate efficient intersystem crossing (ISC) of 49-58%, resulting in TTA-UC with quantum yields of 4.7% and 6.9%, respectively. The analysis of the elementary steps of the TTA-UC process indicates that heavy-atom-free donor-acceptor dyads are less effective than their noble metal counterparts, but may equal them in the future if the right combination of solvent, donor-acceptor sensitizer structure, and new luminescent molecules as TTA-UC emitters can be found.

Harvesting Sub-bandgap Photons via Upconversion for Perovskite Solar Cells.

Lanthanide-based upconversion (UC) allows harvesting sub-bandgap near-infrared photons in photovoltaics. In this work, we investigate UC in perovskite solar cells by implementing UC single crystal BaF2:Yb3+, Er3+ at the rear of the solar cell. Upon illumination with high-intensity sub-bandgap photons at 980 nm, the BaF2:Yb3+, Er3+ crystal emits upconverted photons in the spectral range between 520 and 700 nm. When tested under terrestrial sunlight representing one sun above the perovskite's bandgap and sub-bandgap illumination at 980 nm, upconverted photons contribute a 0.38 mA/cm2 enhancement in the short-circuit current density at lower intensity. The current enhancement scales non-linearly with the incident intensity of sub-bandgap illumination, and at higher intensity, 2.09 mA/cm2 enhancement in current was observed. Hence, our study shows that using a fluoride single crystal like BaF2:Yb3+, Er3+ for UC is a suitable method to extend the response of perovskite solar cells to near-infrared illumination at 980 nm with a subsequent enhancement in current for very high incident intensity.

Interface Pattern Engineering in Core-Shell Upconverting Nanocrystals: Shedding Light on Critical Parameters and Consequences for the Photoluminescence Properties.

Advances in controlling energy migration pathways in core-shell lanthanide (Ln)-based hetero-nanocrystals (HNCs) have relied heavily on assumptions about how optically active centers are distributed within individual HNCs. In this article, it is demonstrated that different types of interface patterns can be formed depending on shell growth conditions. Such interface patterns are not only identified but also characterized with spatial resolution ranging from the nanometer- to the atomic-scale. In the most favorable cases, atomic-scale resolved maps of individual particles are obtained. It is also demonstrated that, for the same type of core-shell architecture, the interface pattern can be engineered with thicknesses of just 1 nm up to several tens of nanometers. Total alloying between the core and shell domains is also possible when using ultra-small particles as seeds. Finally, with different types of interface patterns (same architecture and chemical composition of the core and shell domains) it is possible to modify the output color (yellow, red, and green-yellow) or change (improvement or degradation) the absolute upconversion quantum yield. The results presented in this article introduce an important paradigm shift and pave the way toward the emergence of a new generation of core-shell Ln-based HNCs with better control over their atomic-scale organization.

Photon Upconversion for Photovoltaics and Photocatalysis: A Critical Review.

Opportunities for enhancing solar energy harvesting using photon upconversion are reviewed. The increasing prominence of bifacial solar cells is an enabling factor for the implementation of upconversion, however, when the realistic constraints of current best-performing silicon devices are considered, many challenges remain before silicon photovoltaics operating under nonconcentrated sunlight can be enhanced via lanthanide-based upconversion. A photophysical model reveals that >1-2 orders of magnitude increase in the intermediate state lifetime, energy transfer rate, or generation rate would be needed before such solar upconversion could start to become efficient. Methods to increase the generation rate such as the use of cosensitizers to expand the absorption range and the use of plasmonics or photonic structures are reviewed. The opportunities and challenges for these approaches (or combinations thereof) to achieve efficient solar upconversion are discussed. The opportunity for enhancing the performance of technologies such as luminescent solar concentrators by combining upconversion together with micro-optics is also reviewed. Triplet-triplet annihilation-based upconversion is progressing steadily toward being relevant to lower-bandgap solar cells. Looking toward photocatalysis, photophysical modeling indicates that current blue-to-ultraviolet lanthanide upconversion systems are very inefficient. However, hope remains in this direction for organic upconversion enhancing the performance of visible-light-active photocatalysts.

Interplay of structural dynamics and electronic effects in an engineered assembly of pentacene in a metal-organic framework.

Charge carrier mobility is an important figure of merit to evaluate organic semiconductor (OSC) materials. In aggregated OSCs, this quantity is determined by inter-chromophoric electronic and vibrational coupling. These key parameters sensitively depend on structural properties, including the density of defects. We have employed a new type of crystalline assembly strategy to engineer the arrangement of the OSC pentacene in a structure not realized as crystals to date. Our approach is based on metal-organic frameworks (MOFs), in which suitably substituted pentacenes act as ditopic linkers and assemble into highly ordered π-stacks with long-range order. Layer-by-layer fabrication of the MOF yields arrays of electronically coupled pentacene chains, running parallel to the substrate surface. Detailed photophysical studies reveal strong, anisotropic inter-pentacene electronic coupling, leading to efficient charge delocalization. Despite a high degree of structural order and pronounced dispersion of the 1D-bands for the static arrangement, our experimental results demonstrate hopping-like charge transport with an activation energy of 64 meV dominating the band transport over a wide range of temperatures. A thorough combined quantum mechanical and molecular dynamics investigation identifies frustrated localized rotations of the pentacene cores as the reason for the breakdown of band transport and paves the way for a crystal engineering strategy of molecular OSCs that independently varies the arrangement of the molecular cores and their vibrational degrees of freedom.

Bimolecular and Auger Recombination in Phase-Stable Perovskite Thin Films from Cryogenic to Room Temperature and Their Effect on the Amplified Spontaneous Emission Threshold.

Recently, continuous-wave (CW) lasing was demonstrated at room temperature in quasi-2D perovskites. For 3D films, CW lasing at room temperature remains challenging. Issues hampering 3D materials include the temperature dependence of the (a) distribution of carrier energies, (b) buildup of photoinduced nonradiative channels, and (c) rates of bimolecular versus Auger recombination. We study the latter in a phase-stable 3D perovskite using high-index substrates to completely suppress amplified spontaneous emission (ASE). The bimolecular recombination coefficient decreases from 80 to 290 K (from (6.4 to 1.1) × 10-10 cm-3 s-1), whereas the Auger coefficient stays constant at 3 × 10-29 cm-6 s-1. Above 250 K, the Auger rate exceeds the bimolecular rate at carrier densities corresponding to the ASE threshold. At lower temperatures, the decrease in the bimolecular rate coefficient with increasing temperature and the fraction of photoluminescence in the ASE band determine the temperature dependence of the ASE threshold.

Rare-earth coordination polymers with multimodal luminescence on the nano-, micro-, and milli-second time scales.

We present a coordination polymer based on rare-earth metal centers and carboxylated 4,4'-diphenyl-2,2'-bipyridine ligands. We investigate Y3+, Lu3+, Eu3+, and a statistical mixture of Y3+ with Eu3+ as metal centers. When Y3+ or Lu3+ is exclusively present in the coordination polymer, biluminescence from the ligand is observed: violet emission from the singlet state (417 nm, 0.9 ns lifetime) and orange emission from the triplet state (585 nm, 76 ms (Y3+) and 31 ms (Lu3+)). When Eu3+ is present in a statistical mixture with Y3+, red emission from the Eu3+ (611 nm, ∼ 500 µs ) is observed in addition to the ligand emissions. We demonstrate that this multi-mode emission is enabled by the immobility of singlet and triplet states on the ligand. Eu3+ only receives energy from adjacent ligands. Meanwhile, in the broad inhomogeneous distribution of ligand energies, higher energy states favor singlet emission, whereas faster intersystem crossing in the more stabilized ligands enhances their contribution to triplet emission.

Experimental validation of a modeling framework for upconversion enhancement in 1D-photonic crystals.

Photonic structures can be designed to tailor luminescence properties of materials, which becomes particularly interesting for non-linear phenomena, such as photon upconversion. However, there is no adequate theoretical framework to optimize photonic structure designs for upconversion enhancement. Here, we present a comprehensive theoretical model describing photonic effects on upconversion and confirm the model's predictions by experimental realization of 1D-photonic upconverter devices with large statistics and parameter scans. The measured upconversion photoluminescence enhancement reaches 82 ± 24% of the simulated enhancement, in the mean of 2480 separate measurements, scanning the irradiance and the excitation wavelength on 40 different sample designs. Additionally, the trends expected from the modeled interaction of photonic energy density enhancement, local density of optical states and internal upconversion dynamics, are clearly validated in all experimentally performed parameter scans. Our simulation tool now opens the possibility of precisely designing photonic structure designs for various upconverting materials and applications.

Crystalline assembly of perylene in metal-organic framework thin film: J-aggregate or excimer? Insight into the electronic structure.

The spatial orientation of chromophores defines the photophysical and optoelectronic properties of a material and serves as the main tunable parameter for tailoring functionality. Controlled assembly for achieving a predefined spatial orientation of chromophores is rather challenging. Metal-organic frameworks (MOFs) are an attractive platform for exploring the virtually unlimited chemical space of organic components and their self-assembly for device optimization. Here, we demonstrate the impact of interchromophore interactions on the photophysical properties of a surface-anchored MOF (SURMOF) based on 3,9-perylenedicarboxylicacid linkers. We predict the structural assembly of the perylene molecules in the MOF via robust periodic density functional theory calculations and discuss the impact of unit topology and π-π interaction patterns on spectroscopic and semiconducting properties of the MOF films. We explain the dual nature of excited states in the perylene MOF, where strong temperature-modulated excimer emission, enhanced by the formation of perylene J-aggregates, and low stable monomer emission are observed. We use band-like and hopping transport mechanisms to predict semiconducting properties of perylene SURMOF-2 films as a function of inter-linker interactions, demonstrating both p-type and n-type conduction mechanisms. Hole carrier mobility up to 7.34 cm2Vs-1is predicted for the perylene SURMOF-2. The results show a promising pathway towards controlling excimer photophysics in a MOF while controlling charge carrier mobility on the basis of a predictive model.