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In this study,we conducted a comprehensive investigation of newly synthesized fullerene derivatives developed for potential application in perovskite solar cells (PSCs). We explored three novel dihydrofuran-fused C60 fullerene derivatives (13, 14, and 15) that we respecifically designed to enhance solubility and interaction with the substrate, fluorine-dopedtinoxide (FTO). A comparative analysis was performed, with reference to the widely used phenyl-C61-butyric acid methyl ester (PCBM) and compound 12, from which 13, 14, and 15 are derived, to assess the impact of sugar units on materials properties.The synthesized compounds demonstrated significant solubility in common organic solvents, a critical factor in their potential application in wet-processed PSCs. Our investigation included electrochemical property analysis, thin film deposition, surface characterization, and electrochemical impedance spectroscopy (EIS). EIS measurements unveiled key in sights into charge transfer properties at the electrode/electrolyte interface, making the compounds attractive candidates for electron transport layers (ETLs) in PSCs.

Electrochemically deposited nickel coatings from sulfamate baths without/with lab-made biosilica (SiO2) particles on the Si(100) substrate were produced. Different galvanostatic regimes were used: direct current (DC), pulse current (PC), and pulse-reverse current (PRC) regimes. The phase structure of the synthesized silica nanoparticles from rice husks was obtained using XRD and FE-SEM. The MMC-Ni/SiO2 and free Ni coatings were characterized using FE-SEM, AFM, the micro indentation Vickers technique, and the drop sessile method in order to investigate structure, roughness, microhardness, and wettability. The optimal deposition parameters were obtained with an emphasis on their potential application as micro mounting coatings.

This study aims to determine the maximum possible energy conversion efficiency of visibly transparent solar cells using the detailed balance limit (also known as the Shockley–Queisser limit) and compare it to the efficiency of traditional single-junction solar cells. To achieve this, a new optical nanoantenna has been designed to absorb incoming light selectively, enhancing the average visible transmission while maintaining high absorption in the infrared and UV regions. The color appearance of the antennas has also been evaluated through colorimetrical characterization. Our findings indicate that it is possible to achieve high average visible transparency and energy conversion efficiency of over 80 and 18%, respectively, by carefully selecting semiconductor materials. Such solar cells are versatile enough to be integrated seamlessly into smart windows, agrivoltaic concepts in open and protected cultivation, mobile devices, and appliances without compromising their appearance or functionality. The dimensions and optics of the proposed antennas and visibly transparent solar cells have been thoroughly discussed.

In this study, we conducted a comprehensive investigation of newly synthesized fullerene derivatives developed for potential application in perovskite solar cells (PSCs). We explored three novel dihydrofuran-fused C60 fullerene derivatives (13, 14, and 15) that were specifically designed to enhance solubility and interaction with the substrate, fluorine-doped tin oxide (FTO). A comparative analysis was performed, with reference to the widely used phenyl-C61-butyric acid methyl ester (PCBM) and compound 12, from which 13, 14, and 15 are derived, to assess the impact of sugar units on materials properties. The synthesized compounds demonstrated significant solubility in common organic solvents, a critical factor in their potential application in wet-processed PSCs. Our investigation included electrochemical property analysis, thin film deposition, surface characterization, and electrochemical impedance spectroscopy (EIS). EIS measurements unveiled key insights into charge transfer properties at the electrode/electrolyte interface, making the compounds attractive candidates for electron transport layers (ETLs) in PSCs.

In this study, different forms of copper films were electrodeposited (ED) on silicon wafer, copper and brass foils. The effect of monocrystalline Si(111) surface cleaning method and electrodeposition conditions and regimes (frequency in the pulsating current (PC) regime, an addition of additives in electrolyte for the constant galvanostatic (DC) regime, and thickness) on surface morphology and wettability of copper films was investigated. Optical microscopy equipped with highresolution camera, scanning electron microscopy (SEM) and an atomic force microscopy (AFM) were used for thin film characterization and to evaluate wettability of copper films. The sessile drop method was used for the measurement of water contact angle. According to the obtained results, choice of electrolyte used in ED greatly affects wettability of copper films. It was also shown that copper films electrodeposited from basic sulfate electrolyte with varying current regimes frequencies, thicknesses, and cathode types have opposite trends between roughness parameter values and the water contact angle value. Structural-morphological changes of a film or bulk solid surface are key parameters in determining wettability properties and the analysis of the wetting angle oscillations, but not the only one.

Polymer-fullerene blends based on poly(3-hexylthiophene-2,5-diyl) (P3HT) and phenyl-C61-butyric-acid methyl ester (PCBM) have been extensively studied as promising bulk heterojunction materials for organic semiconductor devices with improved performance. In these donor–acceptor systems where the bulk morphology plays a crucial role, the generation and subsequent decay mechanisms of photoexcitation species are still not completely understood. In this work, we use femtosecond transient absorption spectroscopy to investigate P3HT:PCBM diodes under the influence of applied static electric fields in comparison to P3HT:PCBM thin films. At the same time, we try to present a detailed overview about work already done on these donor–acceptor systems. The excited state dynamics obtained at 638 nm from P3HT:PCBM thin films are found to be similar to those observed earlier in neat P3HT films, while those obtained in the P3HT:PCBM devices are affected by field-induced exciton dissociation, resulting not only in comparatively slower decay dynamics, but also in bimolecular deactivation processes. External electric fields are expected to enhance charge generation in the investigated P3HT:PCBM devices by dissociating excitons and loosely bound intermediate species like polaron pairs (PPs) and charge transfer (CT) excitons, which can already dissociate only due to the intrinsic fields at the donor–acceptor interfaces. Our results clearly establish the formation of PP-like transient species different from CT excitons in the P3HT:PCBM devices as a result of a field-induced diffusion-controlled exciton dissociation process. We find that the loosely bound transient species formed in this way also are reduced in part via a bimolecular annihilation process resulting in charge loss in typical donor–acceptor P3HT:PCBM bulk heterojunction semiconductor devices, which is a rather interesting finding important for a better understanding of the performance of these devices.

Perovskite/silicon tandem solar cells are considered as one of the cost-effective solutions for determining high energy conversion efficiencies. Efficient photon management allows improving light incoupling in solar cells by reducing optical losses. The optics relies upon the interface morphology, and consequently, the growth mechanism of the top cell on the bottom cell is crucial for the implementation of efficient perovskite/silicon tandem solar cells. To describe the interface morphologies of perovskite/silicon tandem solar cells, a three-dimensional surface algorithm is used that allows investigating the perovskite solar cells deposited on the textured crystalline silicon solar cells. We distinguish between two extreme cases in which the film grows only in the direction of the substrate normal or in the direction of the local surface normal. The growth mode has significant influence on the film roughness, the effective thickness of the film, the optics of the solar cell, and the photovoltaic parameters. The optics is investigated by finite-difference time-domain simulations. The influence of the interface morphology on the photovoltaic parameters is discussed, and guidelines are provided to reach high short-circuit current density and energy conversion efficiency.

A blue-light emitting material based on a boron complex containing heteroaromatic phosphonate ligand is synthesized and characterized. The Phospho-Fries rearrangement is used in the synthesis route of the ligand as a convenient method of introducing phosphonate groups into phenols. Structural, thermal and photophysical properties of the resulting oxazaborinin phosphonate compound have been characterized. DFT geometry optimizations were studied as well as the spatial position and symmetry of the HOMO and LUMO. Good thermal stability up to 250 °C enables vacuum deposition methods next to solution processing. Combining the work function with the optical band gap from UV-Vis measurements shows that band alignment is possible with standard contact materials. Photoluminescence reveals an emission peak at 428 nm, which is suitable for a blue light-emitter.

The generation and decay mechanisms of polaron pairs in organic semiconductor-based optoelectronic devices under operational conditions are relevant for a better understanding of photophysical processes affecting the device performance, since the possible occurrence of a polaron pair introduces an intermediate step in exciton dissociation into fully separated charge carriers. The role played by static electric fields in polaron-pair dynamics is important but poorly understood or not investigated in detail. In this work, insights into the polaron-pair dynamics in neat poly(3-hexylthiophene-2,5-diyl) (P3HT) thin films and P3HT films sandwiched between electrical contacts with an applied external static electric field are probed using femtosecond pump–probe transient absorption spectroscopy. Asymmetric contacts result in P3HT devices with application-related diode characteristics. Consistent with the electric field-induced dissociation of oppositely charged species, we show that polaron-pair dissociation into charge carriers occurs in the P3HT device more significantly with increasing reverse bias, and that this process follows an initial instantaneous polaron-pair photoabsorption quenching due to a pronounced immediate loss of primary photoexcitation species (hot excitons). Furthermore, we show that the net-electric field present in the P3HT diode (including built-in-potential at 0 V bias) results in a more complex dynamics with new findings as compared to the neat-P3HT thin film case. Indeed, besides polaron pairs directly originating from hot excitons, we experimentally observe polaron-pair formation during exciton dissociation via a field-mediated generation process, resulting in a slower contribution to the overall decay dynamics. Moreover, unlike in the external electric field-free P3HT film, bimolecular annihilation processes clearly appear as an additional loss channel when a field is applied and hence have an impact on carrier generation performance in a worki

A new device design of microcrystalline silicon thin-film solar cell allows for approaching the geometric light-trapping limit. The solar cell is based on triangular textured surfaces in combination with optimized front and back contacts with very low optical losses. In comparison to crystalline silicon solar cells with record energy conversion efficiency the material usage of the thin-film solar cells is reduced to 1–2%, while exhibiting the potential to achieve short circuit current densities of more than 80% of their counterparts. The short circuit current density of the thin-film solar cells is approaching the geometric light-trapping limit commonly known as the Yablonovitch limit under perpendicular incidence. The design of the solar cell is described considering the electrical and optical properties of the textured solar cell.

Vertically integrated color sensors with plasmonic reflectors are realized. The complete color information is detected at each color pixel of the sensor array without using optical filters. The spectral responsivity of the sensor is tuned by the applied electric bias and the design of the plasmonic reflector. By introducing an interlayer between the lossy metal back reflector and the sensor, the reflectivity can be modified over a wide spectral range. The detection principle is demonstrated for a silicon thin film detector prepared on a textured silver back reflector. The sensor can be used for RGB color detection replacing conventional color sensors with optical filters. Combining detectors with different spectral reflectivity of the back reflector allows for the realization of multispectral color sensors covering the visible and the near-infrared spectral range.

The perovskite material system allows for the realization of perovskite/silicon tandem solar cells with high energy conversion efficiencies at low cost. To realize such solar cells, the device geometry, the device processing, and the contact materials have to be modified in comparison to single junction perovskite solar cells. In this study, perovskite/silicon tandem solar cells are designed allowing for the generation of short-circuit current densities and energy conversion efficiencies exceeding 20 mA cm−2 and 30%, while using realistic device structures. High short-circuit current densities can be achieved by minimizing reflection losses and optical losses of the contact layers. A hybrid approach is used to investigate the optics by combining finite-difference time-domain simulations with experimental measurements. Details on the nanophotonic design will be provided and discussed.

Metal-mesh based electrode systems are a highly conductive, versatile, and inexpensive alternative to ITO-electrodes for organic photovoltaic (OPV) cells. However, they do not offer full surface conductivity and are, therefore, usually combined with an additional conductive layer (e.g. PEDOT:PSS), which enables lateral charge-transport in the area in between the metal tracks. The sheet conductivity of this additional lateral conductive layer (LCL) needs to be carefully tuned with respect to the distance of the metal tracks to reduce short circuit current (Jsc) losses and additional series resistance due to resistive losses in the LCL material. Usually, this is done via electrical simulation or via analysis of IV-measurements of a large number of devices with different LCL sheet conductivities. Here, we present the light-biased light-beam-induced-current (LB-LBIC) measurement technique as a direct way to visualize current collection losses due to PEDOT:PSS sheet resistance in metal mesh/bus bar based OPV cells. We demonstrate that with LB-LBIC we are not only able to visualize and optimize lateral charge extraction under real-device operation conditions in OPV cells based on a high-resolution metal mesh but can measure the PEDOT:PSS sheet resistance in operating OPV devices as well.

The influence of film formation on light-trapping properties of silicon thin-film solar cells prepared on randomly textured substrates was studied. Realistic interface morphologies were calculated with a three-dimensional (3D) surface coverage algorithm using the measured substrate morphology and nominal film thicknesses of the individual layers as input parameters. Calculated interface morphologies were used in finite-difference time-domain simulations to determine the quantum efficiency and absorption in the individual layers of the thin-film solar cells. The investigation shows that a realistic description of interface morphologies is required to accurately predict the light-trapping properties of randomly textured silicon thin-film solar cells.

This paper presents a simple model of MEMS thermopile based vacuum detector and experimental results obtained for sensors designed and fabricated at IHTM-IMTM. Sensors contain two thermopiles, each with 30 multilayer p(+)Si/Al thermocouples and p(+)Si or Al heater. Thermal isolating membrane has sandwich structure consisting of sputtered SiO2 and residual n-Si layer. Dependence of output thermopile voltage on pressure was measured for sensors with different membrane thickness. Tests were performed in pressure range (10(-3)-10(5)) Pa. Experimental results were compared with theoretical predictions.