Bulk Heterojunction Upconversion Thin Films Fabricated via One-Step Solution Deposition.

Upconversion of near-infrared light into the visible has achieved limited success in applications due to the difficulty of creating solid-state films with high external quantum efficiency (EQE). Recent developments have expanded the range of relevant materials for solid-state triplet-triplet annihilation upconversion through the use of a charge-transfer state sensitization process. Here, we report the single-step solution-processed deposition of a bulk heterojunction upconversion film using organic semiconductors. The use of a bulk heterojunction thin film enables a high contact area between sensitizer and annihilator materials in this interface-triplet-generation mechanism and allows for a facile single-step deposition process. Demonstrations of multiple deposition and patterning methods on glass and flexible substrates show the promise of this materials system for solid-state upconversion applications.

Anti-mutated citrullinated vimentin antibodies in rheumatoid arthritis; diagnostic utility and association with deformities and disease activity.

Rheumatoid arthritis (RA) is a chronic autoimmune disease with multiple morbidity burdens. Early diagnosis of RA is the main key in management and prevention of disease complications. Much research nowadays is looking for a serological marker with high accuracy in diagnosis of early RA cases. Our aim in this study was to evaluate the role of anti-mutated citrullinated vimentin (anti-MCV) antibodies in the early diagnosis of RA. In addition to compare its diagnostic sensitivity and specificity with anti-cyclic citrullinated peptide antibodies (anti-CCP) and RF antibodies in early versus established RA patients. This prospective cross-sectional study included 80 participants: 40 RA patients (20 early RA patients and 20 established RA patients), 20 patients with other rheumatic diseases (as a disease control group), and 20 apparently healthy participants as normal controls. All participants underwent history taking, clinical examination (general, articular assessment and calculation of disease activity score (DAS28-ESR)) for RA patients, radiological and laboratory investigations (RF, anti-CCP2 and anti-MCV antibodies measurements by ELISA technique). The results showed that the mean values of anti-CCP2 and anti-MCV were significantly increased in RA cases compared to the control groups (p=0.00 and p=0.01, respectively). Anti-MCV had sensitivity and specificity of 63% and 83%, respectively for diagnosing of early RA at area under curve of 0.80 compared to sensitivity and specificity 37% and 100%, respectively for anti-CCP2. Also, both (anti-CCP2 and anti-MCV) had positive significant correlations with ESR (p < 0.001 and p=0.02, respectively), CRP (p=0.01 and p=0.02, respectively) and DAS 28 (p < 0.001 for both). In conclusion, our data indicated that anti-MCV antibodies may represent a valuable marker for diagnosis of early RA cases.

Luminescence Enhancement Due to Symmetry Breaking in Doped Halide Perovskite Nanocrystals.

Metal-halide perovskite nanocrystals have demonstrated excellent optoelectronic properties for light-emitting applications. Isovalent doping with various metals (M2+) can be used to tailor and enhance their light emission. Although crucial to maximize performance, an understanding of the universal working mechanism for such doping is still missing. Here, we directly compare the optical properties of nanocrystals containing the most commonly employed dopants, fabricated under identical synthesis conditions. We show for the first time unambiguously, and supported by first-principles calculations and molecular orbital theory, that element-unspecific symmetry-breaking rather than element-specific electronic effects dominate these properties under device-relevant conditions. The impact of most dopants on the perovskite electronic structure is predominantly based on local lattice periodicity breaking and resulting charge carrier localization, leading to enhanced radiative recombination, while dopant-specific hybridization effects play a secondary role. Our results suggest specific guidelines for selecting a dopant to maximize the performance of perovskite emitters in the desired optoelectronic devices.

Reflections on hosting summer undergraduate researchers in the midst of a pandemic.

The COVID-19 pandemic continues to impact nearly every aspect of our lives, including academic research. In this Matter of Opinion, we reflect on hosting both in-person and virtual undergraduate students during these challenging times.

Serum and Urine Monocyte Chemoattractant Protein-1 as A Markers for Lupus Nephritis.

Lupus nephritis (LN) is a common major organ manifestation and main cause of morbidity and mortality of the disease. We aimed to determine the level of serum and urinary monocyte chemoattractant protein-1(sMCP-1 and uMCP-1) in systemic lupus erythematosus (SLE) patients with and without LN and analyze their association with different clinical and serologic parameters of disease activity. We enrolled 60 female patients with SLE (32 with LN and 28 without LN) and 20 controls.MCP-1 and anti-dsDNA were measured by ELISA. There was statistically significant increase in serum and urinary MCP-1 in all SLE patients (mean=711.59, 676.68 pg/ml respectively) as compared to the control group (mean= 635.70, 632.40 pg/ml respectively), P=0.034, 0.020 respectively. Among patients with LN there was statistically significant increase in sMCP-1 (mean=723.58) compared to the control group (P=0.038, and in uMCP-1 (mean=699.08) compared to patients without LN (mean=651.07) and control group (mean=632.40), P=0.007, 0.002 respectively. Urinary, but not serum MCP-1, positively correlated with 24 hour proteinuria, anti-dsDNA, renal SLEDAI ,biopsy activity index (r=0.362, P=0.004; r=0.303, P=0.019; r= 0.267, P=0.039; r=0.353, P=0.047 respectively) and negatively correlated with serum albumin (r=-0.329, P=0.010).There was statistically significant increase in uMCP-1 and anti-dsDNA in patients with poor response compared to patients with good response to immunosuppressant therapy (P= 0.025; P=0.034 respectively). In conclusion, uMCP-1 is associated with LN and disease activity and may be used as a useful tool for diagnosis and follow up.

Evaluation of autophagy-related genes in Egyptian systemic lupus erythematosus patients.

Disturbances in autophagy are known to be implicated in autoimmune disorders. Many studies have connected polymorphisms in autophagy-related gene 5 (ATG-5) to systemic lupus erythematosus (SLE). Our aim was the determination of the expression level of ATG-5, Beclin-1 and microtubule-associated protein-light chain 3 (LC-3) in Egyptian SLE patients to investigate the impact of disturbances in autophagy genes on the incidence and progression of the disease. Also, we investigated the incidence of single nucleotide polymorphism (SNP) rs573775 in ATG-5 gene among Egyptian SLE patients. Our results showed that the mean levels of Beclin-1, LC-3 and interleukin (IL)-10 transcripts were significantly higher in SLE patients compared to healthy controls. The previous transcripts were positively correlated with SLE Disease Activity Index (SLEDAI). Beclin-1 and LC-3 transcripts were negatively correlated to complement component 3 (C3) levels. Only LC-3 transcripts were negatively correlated to complement component 4 (C4). The rs573775 SNP of ATG-5 with the variant allele was significantly associated with disease susceptibility, conferring a higher risk of SLE development. This variant allele was more prevalent in patients below 30 years, patients with anemia and in patients with anti-double-stranded DNA (dsDNA), confirming the essential role of ATG-5 polymorphism in the susceptibility of Egyptian patients to SLE.

Correlation of Photoluminescence and Structural Morphologies at the Individual Nanoparticle Level.

Single-particle spectroscopy has demonstrated great potential for analyzing the microscopic behavior of various nanoparticles (NPs). However, high-resolution optical imaging of these materials at the nanoscale is still very challenging. Here, we present an experimental setup that combines high sensitivity of time-correlated single-photon counting (TCSPC) techniques with atomic force microscopy (AFM). This system enables single-photon detection with a time resolution of 120 ps and a spatial resolution of 5 nm. We utilize the setup to investigate the photoluminescence (PL) characteristics of both zero-dimensional (0D) and three-dimensional (3D) perovskite nanocrystals and establish a correlation between the particles' sizes, their PL blinking, and the lifetime behavior. Our system demonstrates an unprecedented level of information, opening the door to understanding the morphology-luminescence correlation of various nanosystems.

Near-unity photoluminescence quantum yield in inorganic perovskite nanocrystals by metal-ion doping.

The luminescence and charge transport properties of inorganic CsPbX3 perovskite nanocrystals (NCs) make them attractive candidates for various optoelectronic applications, such as lasing, X-ray imaging, light communication, and light-emitting diodes (LEDs). However, to realize cutting-edge device performance, high-quality NCs with high photoluminescence quantum yields (PLQYs) are essential. Therefore, substantial efforts and progress have been made to attain superior design/engineering and optimization of the inorganic NCs with a focus on surface quality, reduced nonradiative charge carrier recombination centers, and improved colloidal stabilities. Metal-ion doping has been proven to have a robust influence on the electronic band structure, PL behavior, and charge carrier recombination dynamics. Thus, in this perspective, we summarize the recent progress of the significant impact of metal cation doping on the optical properties, including the PL enhancement of CsPbCl3, CsPbBr3, and CsPbI3 perovskite NCs. Moreover, we shed light on the mechanism behind such improved properties. We conclude by recommending possible aspects and strategies to be further explored and considered for better utilization of these doped NCs in thin-film optoelectronic and energy conversion devices.

Direct-Indirect Nature of the Bandgap in Lead-Free Perovskite Nanocrystals.

With record efficiencies achieved in lead halide perovskite-based photovoltaics, urgency has shifted toward finding alternative materials that are stable and less toxic. Bismuth-based perovskite materials are currently one of the most promising candidates among those alternatives. However, the band structures of these materials, including the nature of the bandgaps, remain elusive due to extremely low photoluminescence quantum yield (PLQY) and scattering issues in their thin-film form. Here, we reveal the specific nature of the material's electronic transitions by realizing monodisperse colloidal nanocrystals (NCs) of hexagonal-phase Cs3Bi2X9 perovskites, which afford well-resolved PL features. Interestingly, the PL profile exhibits a dual-spectral feature at room temperature with comparable intensities, based on which we propose an exciton recombination process involving both indirect and direct transitions simultaneously-an observation further supported by temperature-dependent and density functional theory (DFT) calculations. Our findings provide experimental and theoretical insights into the nature of the bandgaps in bismuth halide materials-essential information for assessing their viability in solar cells and optoelectronics.

Engineering Interfacial Charge Transfer in CsPbBr3 Perovskite Nanocrystals by Heterovalent Doping.

Since compelling device efficiencies of perovskite solar cells have been achieved, investigative efforts have turned to understand other key challenges in these systems, such as engineering interfacial energy-level alignment and charge transfer (CT). However, these types of studies on perovskite thin-film devices are impeded by the morphological and compositional heterogeneity of the films and their ill-defined surfaces. Here, we use well-defined ligand-protected perovskite nanocrystals (NCs) as model systems to elucidate the role of heterovalent doping on charge-carrier dynamics and energy level alignment at the interface of perovskite NCs with molecular acceptors. More specifically, we develop an in situ doping approach for colloidal CsPbBr3 perovskite NCs with heterovalent Bi3+ ions by hot injection to precisely tune their band structure and excited-state dynamics. This synthetic method allowed us to map the impact of doping on CT from the NCs to different molecular acceptors. Using time-resolved spectroscopy with broadband capability, we clearly demonstrate that CT at the interface of NCs can be tuned and promoted by metal ion doping. We found that doping increases the energy difference between states of the molecular acceptor and the donor moieties, subsequently facilitating the interfacial CT process. This work highlights the key variable components not only for promoting interfacial CT in perovskites, but also for establishing a higher degree of precision and control over the surface and the interface of perovskite molecular acceptors.

Shape-Tunable Charge Carrier Dynamics at the Interfaces between Perovskite Nanocrystals and Molecular Acceptors.

Hybrid organic/inorganic perovskites have recently emerged as an important class of materials and have exhibited remarkable performance in photovoltaics. To further improve their device efficiency, an insightful understanding of the interfacial charge transfer (CT) process is required. Here, we report the first direct experimental observation of the tremendous effect that the shape of perovskite nanocrystals (NCs) has on interfacial CT in the presence of a molecular acceptor. A dramatic change in CT dynamics at the interfaces of three different NC shapes, spheres, platelets, and cubes, is recorded. Our results clearly demonstrate that the mechanism of CT is significantly affected by the NC shape. More importantly, the results demonstrate that complexation on the NC surface acts as an additional driving force not only to tune the CT dynamics but also to control the reaction mechanism at the interface. This observation opens a new venue for further developing perovskite NCs-based applications.

Molecular-structure Control of Ultrafast Electron Injection at Cationic Porphyrin-CdTe Quantum Dot Interfaces.

Charge transfer (CT) at donor (D)/acceptor (A) interfaces is central to the functioning of photovoltaic and light-emitting devices. Understanding and controlling this process on the molecular level has been proven to be crucial for optimizing the performance of many energy-challenge relevant devices. Here, we report the experimental observations of controlled on/off ultrafast electron transfer (ET) at cationic porphyrin-CdTe quantum dot (QD) interfaces using femto- and nanosecond broad-band transient absorption (TA) spectroscopy. The time-resolved data demonstrate how one can turn on/off the electron injection from porphyrin to the CdTe QDs. With careful control of the molecular structure, we are able to tune the electron injection at the porphyrin-CdTe QD interface from zero to very efficient and ultrafast. In addition, our data demonstrate that the ET process occurs within our temporal resolution of 120 fs, which is one of the fastest times recorded for organic photovoltaics.

Quantum confinement-tunable intersystem crossing and the triplet state lifetime of cationic porphyrin-CdTe quantum dot nano-assemblies.

Here, we report a ground-state interaction between the positively charged cationic porphyrin and the negatively charged carboxylate groups of the thiol ligands on the surface of CdTe quantum dots (QDs), leading to the formation of a stable nanoassembly between the two components. Our time-resolved data clearly demonstrate that we can dramatically tune the intersystem crossing (ISC) and the triplet state lifetime of porphyrin by changing the size of the QDs in the nanoassembly.