Ultra-thin perovskite absorber layers have attracted increasing interest since they are suitable for application in semi-transparent perovskite and tandem solar cells. In this study, size and density ...controlled plasmonic silver nanoparticles are successfully incorporated into ultra-thin perovskite solar cells through a low temperature spray chemical vapor deposition method. Incorporation of Ag nanoparticles leads to a significant enhancement of 22.2% for the average short-circuit current density. This resulted in a relative improvement of 22.5% for the average power conversion efficiency. Characterization by surface photovoltage and photoluminescence provides evidence that the implemented silver nanoparticles can enhance the charge separation and the trapping of electrons into the TiO2 layer at the CH3NH3PbI3/TiO2 interface. The application of these silver nanoparticles therefore has promise to enhance the ultra-thin perovskite solar cells.
Organic–inorganic perovskites are well suited for optoelectronic applications. In particular, perovskite single and perovskite tandem solar cells with silicon are close to their market entry. Despite ...their swift rise in efficiency to more than 21%, solar cell lifetimes are way below the needed 25 years. In fact, comparison of the time when the device performance has degraded to 80% of its initial value (T80 lifetime) of numerous solar cells throughout the literature reveals a strongly reduced stability under illumination. Herein, the various detrimental effects are discussed. Most notably, moisture‐ and heat‐related degradation can be mitigated easily by now. Recently, however, several photoinduced degradation mechanisms have been observed. Under illumination, mixed perovskites tend to phase segregate, while, further, oxygen catalyzes deprotonation of the organic cations. Additionally, during illumination photogenerated charge can be trapped in the NH antibonding orbitals causing dissociation of the organic cation. On the other hand, organic–inorganic perovskites exhibit a high radiation hardness that is superior to crystalline silicon. Here, the proposed degradation mechanisms reported in the literature are thoroughly reviewed and the microscopic mechanisms and their implications for solar cells are discussed.
T80 lifetimes of organic–inorganic perovskite solar cells are strongly reduced under illumination. Various degradation mechanisms are therefore discussed throughout the literature. Degradation by moisture or heat is well understood and mitigation possible. Photoinduced phase segregation and photoinduced dissociation of the organic cation, however, remain unsolved. Recent observations enlighten the underlying microscopic mechanisms and may pave the way for stable perovskites.
Tandem solar cells combining silicon and perovskite absorbers have the potential to outperform state-of-the-art high efficiency silicon single junction devices. However, the practical fabrication of ...monolithic silicon/perovskite tandem solar cells is challenging as material properties and processing requirements such as temperature restrict the device design. Here, we fabricate an 18% efficient monolithic tandem cell formed by a silicon heterojunction bottom- and a perovskite top-cell enabling a very high open circuit voltage of 1.78 V. The monolithic integration was realized vialow temperature processing of the semitransparent perovskite sub-cell where an energetically aligned electron selective contact was fabricated by atomic layer deposition of tin oxide. The hole selective, transparent top contact was formed by a stack of the organic hole transport material spiro-OMeTAD, molybdenum oxide and sputtered indium tin oxide. The tandem cell design is currently limited by the photocurrent generated in the silicon bottom cell that is reduced due to reflectance losses. Based on optical modelling and first experiments, we show that these losses can be significantly reduced by combining optical optimization of the device architecture including light trapping approaches.
The radiation hardness of CH3NH3PbI3‐based solar cells is evaluated from in situ measurements during high‐energy proton irradiation. These organic–inorganic perovskites exhibit radiation hardness and ...withstand proton doses that exceed the damage threshold of crystalline silicon by almost 3 orders of magnitude. Moreover, after termination of the proton irradiation, a self‐healing process of the solar cells commences.
Perovskite solar cells with transparent contacts may be used to compensate for thermalization losses of silicon solar cells in tandem devices. This offers a way to outreach stagnating efficiencies. ...However, perovskite top cells in tandem structures require contact layers with high electrical conductivity and optimal transparency. We address this challenge by implementing large-area graphene grown by chemical vapor deposition as a highly transparent electrode in perovskite solar cells, leading to identical charge collection efficiencies. Electrical performance of solar cells with a graphene-based contact reached those of solar cells with standard gold contacts. The optical transmission by far exceeds that of reference devices and amounts to 64.3% below the perovskite band gap. Finally, we demonstrate a four-terminal tandem device combining a high band gap graphene-contacted perovskite top solar cell (E g = 1.6 eV) with an amorphous/crystalline silicon bottom solar cell (E g = 1.12 eV).
Zinc oxide (ZnO) thin films grown on glass substrates are prepared by means of the Ion Layer Gas Reaction process. The XRD pattern revealed that the ZnO lattice parameters decrease continuously, with ...the increasing of the film thickness, indicating a continuous variation in the compressive strain. The influence of the thickness on the optical, morphological and structural properties of deposited ZnO thin films was investigated. The UV–Vis absorption spectra of deposited thin films were shown to exhibit a blue-shift, resulting in an increase in the optical band gap from 3.13 eV to 3.24 eV. Structural parameters such as crystallite size, lattice parameters, Zn–O bond length, and residual stress have been determined, and the compressive strain (tensile stress) is found to increase with the increasing of spray time and in turn deposited thin film thickness. The PL spectra of deposited ZnO films, show stronger PL intensity with increasing deposited thin film thickness, which confirm the influence of deposited film thickness on the recombination process of charge carriers and thus on its optical properties. These results, were confirmed by the photo-electrochemical experiments. In addition, a wettability alteration and shift from hydrophobic to hydrophilic surface is observed under UV light exposure, which shows that structural defects and surface morphology of deposited thin films were also demonstrated to have a direct impact on deposited films’ optical properties. Furthermore, to further confirm these experimental optical results, theoretical first principle calculations were conducted. In addition, a wettability alteration and shift from hydrophobic to hydrophilic surface is observed under UV light exposure.
The synergistic effect of combining molecular imprinting and surface acoustic wave (SAW) technologies for the selective and label-free detection of sulfamethizole as a model antibiotic in aqueous ...environment was demonstrated. A molecularly imprinted polymer (MIP) for sulfamethizole (SMZ) selective recognition was prepared in the form of a homogeneous thin film on the sensing surfaces of SAW chip by oxidative electropolymerization of m-phenylenediamine (mPD) in the presence of SMZ, acting as a template. Special attention was paid to the rational selection of the functional monomer using computational and spectroscopic approaches. SMZ template incorporation and its subsequent release from the polymer was supported by IR microscopic measurements. Precise control of the thicknesses of the SMZ-MIP and respective nonimprinted reference films (NIP) was achieved by correlating the electrical charge dosage during electrodeposition with spectroscopic ellipsometry measurements in order to ensure accurate interpretation of label-free responses originating from the MIP modified sensor. The fabricated SMZ-MIP films were characterized in terms of their binding affinity and selectivity toward the target by analyzing the binding kinetics recorded using the SAW system. The SMZ-MIPs had SMZ binding capacity approximately more than eight times higher than the respective NIP and were able to discriminate among structurally similar molecules, i.e., sulfanilamide and sulfadimethoxine. The presented approach for the facile integration of a sulfonamide antibiotic-sensing layer with SAW technology allowed observing the real-time binding events of the target molecule at nanomolar concentration levels and could be potentially suitable for cost-effective fabrication of a multianalyte chemosensor for analysis of hazardous pollutants in an aqueous environment.
Molybdenum sulfide, MoS x , is considered as attractive hydrogen evolution catalyst since it is free of noble metals and shows a low overpotential. Especially, amorphous molybdenum sulfide has ...attracted attention because of its high catalytic activity. However, the catalytic mechanism of the hydrogen evolution reaction is not yet fully understood. Therefore, in our study, layers of MoS x were deposited by reactive magnetron sputtering, varying the substrate temperature in the range from room temperature (RT) to 500 °C. The morphology and structure of the films change significantly as a function of temperature, from an amorphous to a highly textured 2H-MoS2 phase. The highest catalytic activity was found for amorphous layers deposited at RT, showing an overvoltage of 180 mV at a current density of −10 mA cm–2 in a 0.5 M sulfuric acid electrolyte (pH 0.3) after electrochemical activation. As detected by Raman spectroscopy, the RT deposited catalyst consists of Mo3S132– and Mo3S122– entities which are interconnected via S22– and S2– ligands. When the potential was swept from +0.2 to −0.3 V vs RHE, a massive release of sulfur in the form of gaseous H2S was observed in the first minutes as detected by differential electrochemical mass spectroscopy (DEMS). After electrochemical cycling for 10 min, the chains of these clusters transformed into a layer-type MoS2–x phase observed by in situ Raman spectroscopy. In this transformation process, H2S formation gradually vanishes and H2 evolution becomes dominant. The transformed phase is considered as a sulfur-deficient molybdenum sulfide characterized by a high number of molybdenum atoms located at the edges of nanosized MoS x islands, which act as catalytically active centers.
Highly efficient perovskite based solar cells have the potential to be a game-changing solar array technology for space applications that can be flexible, truly roll-able, ultra-lightweight and ...highly stowable. Outside earth's magnetic field, however, ionizing radiation causes localized defect states that accumulate and ultimately cause the failure of electronic devices. This study, assesses the radiation hardness of the widely used triple cation based perovskite absorber material, namely Cs
0.05
MA
0.17
FA
0.83
Pb(I
0.83
Br
0.17
)
3
employing 20 and 68 MeV proton irradiation. Therefore,
in situ
measurements of the degradation of the proton induced current as well as the photovoltaic performance during proton irradiation are used as two independent metrics. Both measurements suggest that triple cation perovskites even exceed the radiation hardness of SiC, which is a material often proposed to possess an excellent radiation hardness. Our optimized Cs
0.05
MA
0.17
FA
0.83
Pb(I
0.83
Br
0.17
)
3
based space solar cells reach efficiencies of 18.8% under AM0 illumination and maintain 95% of their initial efficiency even after irradiation with protons at an energy 68 MeV and a total dose of 10
12
p per cm
2
. Degradation under 20 MeV proton irradiation is even lower. Despite the negligible impact on solar cell device performance, this study identifies that proton irradiation is changing the recombination kinetics under low excitation densities profoundly. Dark capacitance-voltage and current-voltage characteristics, photoluminescence spectra as well as photoluminescence and
V
oc
decays are analyzed in depth. Surprisingly, two fold prolonged PL and
V
oc
decay times are observed after proton irradiation. Often, such prolongations are attributed to a reduced charge recombination. Our kinetic model, precisely describing the observed time evolution after photoexcitation, however, establishes the prolonged release of trapped minority charge carriers from proton-radiation induced trap states.
Although highly energetic proton irradiation forms localized trap states in triple cation perovskites, solar cells possess exceptional radiation hardness.
This work demonstrates the determination of macrolide antibiotics in aqueous environments using a screen-printed electrode (SPE) combined with a molecularly imprinted polymer (MIP) prepared from dual ...functional monomers. By employing the reversible covalent interactions between diols of macrolide and boronic acids of 3-aminophenylboronic acid (APBA) as well as the noncovalent interactions between macrolide and m-phenylenediamine (mPD), a dual recognition involving the central macrocyclic lactone exclusive to all macrolides was successfully achieved, thus permitting the possible broad recognition of individual members of the class. The prepared macrolide MIP (mMIP) was characterised by electrochemical and ellipsometric measurements. Following optimization, the sensor demonstrated about four times better recognition for macrolides, including erythromycin (Ery), clarithromycin (Cla), and azithromycin (Azi), than its non-imprinted reference. In addition, low analytical limits were achieved (LOD 1.1–1.6 nM and LOQ 3.8–5.3 nM). Moreover, an excellent selectivity was displayed towards the macrolides in both buffer and tap water samples, and a good recovery (93–108%) of the analytes was achieved. The analytical approach described herein could be further developed as a portable sensing device capable of on-site monitoring of macrolides in environmental water.
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•Electrochemical MIP sensor for nanomolar determination of macrolide antibiotics.•Synergy of covalent and noncovalent imprinting enables class-selective recognition.•Successful analysis of antibiotics in environmental water with good recovery.•Potential for rapid and on-site detection of environmental pollutants displayed.
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