Significant progress has been made in replicating the secondary structures of biomolecules, but more work is needed to mimic their higher-order structures essential for complex functions. This study entails designing periodically grafted aromatic polyamides to explore the possibility of mimicking higher-order structures and related functions. The incompatibility between aromatic hydrocarbon and grafted polyethylene glycol (PEG) chains is utilized for immiscibility-driven phase segregation and their bulk assemblies. Additionally, these polyamides can induce an intrachain folded structure, promoting an organized arrangement of ?-surfaces in phase-segregated domains, distinguishing this research from conventional polymer phase separation. Notably, the incorporation of aromatic guest molecules results in significant enhancements in the structural coherence of these aromatic polyamides. Like structural characterizations, the host-guest complex exhibits superior charge transport potential across the ordered ?-domains than the host polymer alone. The vertical charge transport setup yields a current density of ?10-4 A cm- 2, while the lateral currents in a horizontal setup (?10-10 A) are insignificant, indicating a preferential alignment of ?-domains within the bulk structure. Additionally, substrate surface chemistry influences the orientation of the ?-folded domains, with hydrophilic glass substrates resulting in higher lateral currents (?10-5 A) compared to unmodified glass, highlighting the potential of these materials for electronic applications

Carbon dots (CDs), versatile carbon?based luminescent nanomaterials, offer environmental friendliness, cost?effectiveness, and tunable optical properties for diverse optoelectronic applications, including LEDs, photodetectors, and flexible electronics. These nanoscale materials exhibit unique optical behaviors like highly tunable photoluminescence (PL) and efficient multiphoton up?conversion. This study explores how precursor selection influences CDs' sp²/sp³ hybridization ratios and their optoelectronic properties. CDs were synthesized from four distinct sources: polymeric Polyvinylpyrrolidone (PVP), protein, biomass, and citric acid. Biomass? and protein?derived CDs displayed remarkable photocurrent enhancements under blue light, attributed to balanced sp²/sp³ ratios, while polymer?derived CDs showed limited optoelectronic response. These findings reveal the critical role of precursor composition in tailoring the structural and electronic properties of CDs, offering sustainable pathways for their application in advanced optoelectronic devices.

The hybridization of biomolecules with gold nanoclusters (AuNCs) has emerged as a promising research direction in bioelectronics, extending multidimensional prospects for diverse applications, from wearable health monitoring to advanced medical devices and tissue engineering. Here, we report a hybrid of bovine serum albumin (BSA) protein and gold nanoclusters of various concentrations to harness the distinctive properties of gold nanoclusters and enhance the electronic functionalities of biomolecules. Self-assembled monolayers (SAMs) of hybrid materials demonstrate enhanced electrical conduction with a film thickness of 10–15 nm as obtained from atomic force microscopy topographical images, revealing minimal aggregation. Current–voltage (I–V) characteristics at ±0.5 V showed significantly higher current densities for optimized hybrid material (BSA-Au6) SAMs, reaching 150 A/cm2. Compared to prior studies on BSA and metal hybrid thin films, the observed 100-fold enhancement in electrical conductivity for AuNC-doped SAMs highlights the novelty of this work. Moreover, our study with different AuNC concentrations demonstrated that six equivalents of AuNCs significantly boosted conductivity due to efficient electron transport mechanisms, which was further investigated with electrical impedance measurements. Our findings provide valuable insights into the underlying electronic transport mechanisms across hybrid materials for applications in bioelectronics and molecular electronics, marking a breakthrough compared to conventional protein films.

The cofactors of proteins dictate the charge transport mechanism across molecular junctions when self-assembled protein monolayers are sandwiched between two metal electrodes. Here, we summarized how the chemical coordination nature of cofactors in various proteins modulates electrical conductance by investigating electronic transport studies across different protein-based molecular junctions under various forces applied under the AFM tip. We have utilized several numerical techniques of electronic transport to analyse the experimentally obtained current-voltage measurements across various protein-based molecular junctions and depicted the origin of electronic modulation in the electrical conductance under different external stimuli. We could also find the origin of electronic conductance modulation under external stimuli at various applied forces by obtaining several analytical transport parameters such as energy barrier, coupling strength, and electrical conductance values. Utilizing density-functional-theory calculations, we further validate that the electronic density of states present in the cofactors within the proteins dominates the electronic transport behaviours across protein-based molecular junctions. Our findings reveal the limiting factor for applying various external stimuli on different proteins, which could be further valuable in bioelectronic applications. We have also found that the organic cofactor containing protein follows all the tunneling mechanism-related numerical transport models and the electronic transport across proteins with pure inorganic cofactors follows Landauer transport formalism. © 2024 IOP Publishing Ltd.

Perovskite solar cells made of inorganic cesium lead bromide (CsPbBr3) display unusually high open-circuit potentials. Yet, their photovoltaic efficiency is still lagging behind that of iodide-based halide perovskites. In this study, a multistep solution spin coating process is used to create a CsPbBr3 film. The CsPbBr3 perovskite film consists of flat and rounded grains, and the photocurrent of each grain type is imbalanced. Interestingly, a significant current increase in flat grains is observed when conducting atomic force microscopy (c-AFM) at the nanoscale after the addition of methyl ammonium bromide (MABr) as an additive. The addition of MABr results in good optoelectronic quality of perovskite films with highly conductive grains and enables better charge transport and hence improved power conversion efficiency. © 2024 RSC.

Over a decade, researchers have depicted remarkable optoelectronic properties of halide?based organic–inorganic perovskites and demonstrated impressive power conversion efficiency in photovoltaic applications, starting from 3.9% to 26.1%. The optoelectronic properties of halide?based perovskites are significantly influenced by the crystal form and crystallization process. There are two common forms of halide?based perovskites: polycrystalline films and single?crystal. In polycrystalline thin films, multiple grain boundaries lead to ion migration, surface flaws, and instability, making them unsuitable for device applications. In contrast, single?crystal halide?based perovskites are stable and exhibit exceptional features like long carrier diffusion lengths and low trap density. Although research on polycrystalline halide?based perovskite thin films is currently intense, investigations on single crystals are still in their early stages. This review article discusses single?crystal perovskite halide growth methods and their use in optoelectronic devices, as crystal growth affects solar cells, light?emitting diodes, lasers, photodetectors, and other devices.

Molecular junctions are formed by wedging molecules between two metal electrodes. In addition to the conventional parameters of the metal–molecule–metal junction, such as the work function of electrodes and the molecules' energy gap, molecule-electrode electronic coupling strength also plays a vital role in modulating the electronic properties of the molecular junction under external stimuli. We have examined the electron transport across bacteriorhodopsin molecular junction under various external forces applied at the AFM tip in the electrical characterization process with different humidity values under dark and illumination conditions. We have analyzed experimentally obtained I–V data under these external stimuli using tunneling-based transport modeling techniques such as differential conductance, law of corresponding states, normalized differential conductance, transition voltage spectroscopy, and Landauer transport formalism. We have also calculated several transport parameters which play a crucial role in finding the origin of conductance modulation under the external stimuli. We found that before particular humidity conditions, the modulation in the conductance is due to the variation in coupling strength, which is due to the modulation in the electrostatic environment of retinal chromophores of a protein by changing its structure under various external stimuli.

Here we report how the chemical functionalization of the bridge molecule influences the electronic properties of conjugated terthiophene and the electronic coupling, i.e., the linkage between molecule and electrode, using density functional theory (DFT) methods. Furthermore, we explore the modulation in electron transport properties of molecular junctions with various functional derivatives utilizing a combination of DFT and electron transport non-equilibrium Green’s function (NEGF) calculations.

Self-assembled nanostructures obtained from various functional ?-conjugated organic molecules have been able to draw substantial interest due to their inherent optical properties, which are imperative for developing optoelectronic devices, multiple-color-emitting devices with color-tunable displays, and optical sensors. These ?-conjugated molecules have proven their potential employment in various organic electronic applications. Therefore, the stimuli-responsive fabrication of these ?-conjugated systems into a well-ordered assembly is extremely crucial to tuning their inherent optical properties for improved performance in organic electronic applications. To this end, herein, we have designed and synthesized a functional ?-conjugated molecule (TP) having phenanthro[9,10-d]imidazole with terpyridine substitution at the 2 position and its corresponding metal complexes (TPZn and (TP)Zn). By varying the polarity of the self-assembly medium, TP, TPZn, and (TP)Zn are fabricated into well-ordered superstructures with morphological individualities. However, this medium polarity-induced self-assembly can tune the inherent optical properties of TP, TPZn, and (TP)Zn and generate multiple fluorescence colors. Particularly, this property makes them useful for organic electronic applications, which require adjustable luminescence output. More importantly, in 10% aqueous-THF medium, TPZn exhibited H-type aggregation-induced white light emission and behaved as a single-component white light emitter. The experimentally obtained results of the solvent polarity-induced variation in optical properties as well as self-assembly patterns were further confirmed by theoretical investigation using density functional theory calculations. Furthermore, we investigated the I-V characteristics, both vertical and horizontal, using ITO and glass surfaces coated with TP, TPZn, and (TP)Zn, respectively, and displayed maximum current density for the TPZn-coated surface with the order of measured current density TPZn > TP > (TP)Zn. This observed order of current density measurements was also supported by a direct band gap calculation associated with the frontier molecular orbitals using the Tauc plot. Hence, solvent polarity-induced self-assembly behavior with adjustable luminescence output and superior I-V characteristics of TPZn make it an exceptional candidate for organic electronic applications and electronic device fabrication.

Sputter grown copper (Cu) and titanium dioxide (TiO 2 ) based transparent solar heat rejecting film has been developed on glass substrates at room temperature for energy saving smart window applications. The performance of as-deposited ultra-thin TiO 2 /Cu/TiO 2 multilayers was elucidated, wherein the visible transmittance of the multilayer significantly depends on the crystal quality of TiO 2 layers. In-situ nanocrystal engineering of TiO 2 films with optimized sputtering power improves crystallinity of nano-TiO 2 domains. The transparent heat regulation (THR) coating with an average transmittance of ?70% over the visible spectral regime and infra-red reflectance of ?60% at 1200 nm was developed at room temperature. Optical characterization, X-ray diffraction (XRD), high resolution-transmission electron microscopy (HR-TEM) and atomic force microscopy (AFM) have been utilized to analyze the crystallinity of TiO 2 and quality of the multilayered structure. TiO 2 /Cu/TiO 2 based prototype device has been demonstrated for the energy saving smart windows application.

Throughout a few years, carrier transport studies across HaP single crystals have gained enormous importance for current generation photovoltaic and photodetector research with their superior optoelectronic properties compared to commercially available polycrystalline materials. Utilizing the room-temperature solution-grown method, we synthesized MAPbBrcrystals and examined their electrical transport properties. Although the X-ray diffraction reveals the cubical nature of the crystals, we have observed anisotropy in the electrical transport behavior and variation in dielectric constant across the three opposite faces of the crystals of mm dimensions. The face with a higher dielectric constant depicts improved parameters from electrical characteristics such as lower trap densities and higher mobility values. We further explore the origin of its anisotropic nature by performing X-ray diffraction on three opposite faces of crystals. Our studies define the specific faces of cuboid-shaped MAPbBrcrystals for efficient electrical contact in the fabrication of optoelectronic devices.

Hybrid organic-inorganic perovskites (HOIPs) have become promising candidates for future photovoltaics (PV) with significant advancements in their performance over recent years. Along with PV, HOIPs possess applications in photodiodes, photodetectors, photocatalysis, and memory devices. Generally, perovskites are structurally flexible to accommodate various cations on their respective sites through compositional engineering, thereby altering the characteristic material properties of the system. HOIPs have ABX structures, in which organic or inorganic moieties occupy the monovalent ‘A’ site. In this work, the effect of formamidinium (FA) on the optical and morphological properties of HOIPs using two different bromide perovskites - FAMACsPbBr and MACsPbBr - is examined. After ‘FA’ modification, we noticed a reduction in the bandgap and an increase in the grain size of the FAMACsPbBr perovskite compared with the MACsPbBr perovskite. As a result, a better photocurrent response during photoelectrochemical analysis and an improved power conversion efficiency (PCE) for photovoltaic devices were detected with the FA-modified HOIP (FAMACsPbBr).

We report the in-situ, room-temperature synthesis of methylammonium lead bromide CH 3 NH 3 PbBr 3 crystals using N-methyl formamide as a source of methylammonium (MA+) ions during the crystallization process to explore the structural, dielectric, and electronic properties of CH 3 NH 3 PbBr 3 crystals for optoelectronic applications. Optical absorption and radio-luminescence measurements affirm the direct bandgap nature of the crystals. Impedance spectroscopy measurements with various applied AC voltages within the 20 Hz–10 MHz frequency range depict the influence of ionic motions on electrical transport across crystal planes. We have extracted electrical transport parameters in CH 3 NH 3 PbBr 3 crystals from the Nyquist plots, which we found to be distinctly varied wherein two different AC voltage amplitude regimes, broadly for 10–50 mV and 100–500 mV AC voltage range.

Biomolecules such as proteins, peptides being the most crucial life-forms, have an intimate relationship with various life activities for biological functions. Recent, contemporary work with biomolecules mainly focuses on its evolving potential associated with nanoscale electronics where proteins and peptides are integrated as sensing materials. We have explored the optoelectronics functionality of combined proteins known as phycobiliproteins. We have investigated electron transport behavior across the phycobiliproteins films under dark and white light illumination. We affirm that the photochemical activity of the protein is more stable in a solid-state/ thin film with tightly bonded water molecules than its presence in a buffer solution. Furthermore, our studies demonstrate that phycobiliproteins films modulate their electrical conductivity within their different conformation states. We speculate that the electrical conductance variation could originate from the chemical alteration of cysteine-conjugated bilin chromophores to protein and the electrostatic environment around the chromophores.

Two-dimensional molecular junctions (MJs) are mostly developed by sandwiching molecules between two metal electrodes. Charge transport in molecular junctions is not only determined by the difference between work function of electrodes and HOMO/LUMO of the molecule (? energy offset, ?), but also on molecule–electrode electronic coupling strengths (? ). Detailed knowledge of molecule–electrode coupling could reveal its effect on electron transport efficiency. We have examined the modulation of electronic conductance (G) across bio-molecule/protein-based MJs, where electronic coupling strengths were altered via applied mechanical forces on molecules with conducting-AFM probe. We have utilized numerical tunneling transport models which are developed for MJs and calculated G, ?, ? from experimentally obtained current–voltage data. We conclude that the modulation in electronic transport in bio-MJs under applied forces originates from the alteration of ? , which further incites the alteration of physical structure and variation of electrostatics environment around the chromophore of the protein.

Tin dioxide (SnO), the most stable oxide of tin, is a metal oxide semiconductor that finds its use in a number of applications due to its interesting energy band gap that is easily tunable by doping with foreign elements or by nanostructured design such as thin film, nanowire or nanoparticle formation,etc., and its excellent thermal, mechanical and chemical stability. In particular, its earth abundance and non-toxicity make it very attractive for use in a number of technologies for sustainable development such as energy harvesting and storage. This article attempts to review the state of the art of synthesis and properties of SnO, focusing primarily on its application as a transparent conductive oxide (TCO) in various optoelectronic devices and second in energy harvesting and energy storage devices where it finds its use as an electron transport layer (ETL) and an electrode material, respectively. In doing so, we discuss how tin oxide meets the requirements for the above applications, the challenges associated with these applications, and how its performance can be further improved by adopting various strategies such as doping with foreign metals, functionalization with plasma,etc.The article begins with a review on the various experimental approaches to doping of SnOwith foreign elements for its enhanced performance as a TCO as well as related computational studies. Herein, we also compare the TCO performance of doped tin oxide as a function of dopants such as fluorine (F), antimony (Sb), tantalum (Ta), tungsten (W), molybdenum (Mo), phosphorus (P), and gallium (Ga). We also discuss the properties of multilayer SnO/metal/SnOstructures with respect to TCO performance. Next, we review the status of tin oxide as a TCO and an ETL in devices such as organic light emitting diodes (OLEDs), organic photovoltaics (OPV), and perovskite solar cells (including plasma treatment approaches) followed by its use in building integrated photovoltaic (BIPV) applications. Next, we review the impact of SnO, mainly as an electrode material on energy storage devices starting from the most popular lithium (Li)-ion batteries to Li-sulfur batteries and finally to the rapidly emerging technology of supercapacitors. Finally, we also compare the performance of doped SnOwith gallium (Ga) doped zinc oxide (ZnO), the main sustainable alternative to SnOas a TCO and summarize the impact of SnOon circular economies and discuss the main conclusions and future perspectives. It is expected that the review will serve as an authoritative reference for researchers and policy makers interested in finding out how SnOcan contribute to the circular economy of some of the most desired sustainable and clean energy technologies including the detailed experimental methods of synthesis and strategies for performance enhancement.

The charge transport across a molecular junction formed by sandwiching molecules between two electrodes in testbed architectures depends not only on the work function of the metal electrodes and energy gap of the molecules but also on the efficacy of the molecule–electrode electronic coupling. Insights into such molecule–electrode coupling would help to understand the relation between the coupling strength and electron transport processes. With this aim, the optoelectronic modulation across bacteriorhodopsin-based molecular junctions has been studied using experimental current–voltage traces obtained by conducting-probe atomic force microscopy under various illuminations. The energy barrier (?) , molecule–electrode coupling (?), and other transport parameters were determined utilizing the Landauer model with a single-Lorentzian transmission function, transition voltage spectroscopy, and the law of corresponding states in the universal tunneling model approach. The findings reveal that the optoelectronic modulation of bacteriorhodopsin molecular junctions originate from alteration of the molecule–electrode coupling, which could originate from modulation of electronic states and the electrostatic environment of retinal chromophores made of the protein under dark and green or green–blue illumination conditions.

We have developed an electrical circuit-based compact numerical fitting model to determine industry-related physical parameters of solar cells utilizing only 3–8 current–voltage coordinate points without any specific selection of an experimental coordinate axis. The proposed compact numerical fitting model was effectively tested to determine the peak power point, fill factor and efficiencies for organic and inorganic solar cells, as well as for solar panels. This research facilitates cost-effective energy management of solar modules and farms.

Thermochromic material coating on windows or thermochromic paints on building reflects the solar radiation, especially the infrared regime and transmit visible radiation regime. This enables to use thermochromic material for smart window/building applications. This chapter introduces the physics of organic and inorganic thermochromic materials, their developments and applications for maintaining building temperature naturally, with reducing electricity usage. We have reviewed different methods utilized recently to develop thermochromic paints or thin films on plastic or glass windows. Thermochromic smart coating on glass or plastic substrates are designed as an intelligent system that can actively adjust transmission/reflection of sun light by coordinating its phase transition with building's lighting and temperature in order to maintain the environment desired by a building occupant while minimizing energy loss.

Successful integration of proteins in solid-state electronics requires contacting them in a non-invasive fashion, with a solid conducting surface for immobilization as one such contact. The contacts can affect and even dominate the measured electronic transport. Often substrates, substrate treatments, protein immobilization, and device geometries differ between laboratories. Thus the question arises how far results from different laboratories and platforms are comparable and how to distinguish genuine protein electronic transport properties from platform-induced ones. We report a systematic comparison of electronic transport measurements between different laboratories, using all commonly used large-area schemes to contact a set of three proteins of largely different types. Altogether we study eight different combinations of molecular junction configurations, designed so that A geo of junctions varies from 10 5 to 10 ?3 ?m 2. Although for the same protein, measured with similar device geometry, results compare reasonably well, there are significant differences in current densities (an intensive variable) between different device geometries. Likely, these originate in the critical contact-protein coupling (?contact resistance), in addition to the actual number of proteins involved, because the effective junction contact area depends on the nanometric roughness of the electrodes and at times, even the proteins may increase this roughness. On the positive side, our results show that understanding what controls the coupling can make the coupling a design knob. In terms of extensive variables, such as temperature, our comparison unanimously shows the transport to be independent of temperature for all studied configurations and proteins. Our study places coupling and lack of temperature activation as key aspects to be considered in both modeling and practice of protein electronic transport experiments.

We review the status of protein-based molecular electronics. First, we define and discuss fundamental concepts of electron transfer and transport in and across proteins and proposed mechanisms for these processes. We then describe the immobilization of proteins to solid-state surfaces in both nanoscale and macroscopic approaches, and highlight how different methodologies can alter protein electronic properties. Because immobilizing proteins while retaining biological activity is crucial to the successful development of bioelectronic devices, we discuss this process at length. We briefly discuss computational predictions and their connection to experimental results. We then summarize how the biological activity of immobilized proteins is beneficial for bioelectronic devices, and how conductance measurements can shed light on protein properties. Finally, we consider how the research to date could influence the development of future bioelectronic devices.