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A focus on charge carrier recombination and energy conversion efficiency in nanohybrid photovoltaics
摘要： We investigated the effect of multiwall carbon nanotubes grafted with poly(3-dodecylthiophene) (CNT-graft-PDDT) on the performance of poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester photovoltaic cells. It is demonstrated that the presence of small amounts of these modified CNTs improves the structural organization of the films as evidenced by the grazing incidence wide-angle X-ray scattering studies. The ultraviolet–visible (UV–Vis) spectroscopy revealed that the incorporation of CNT-graft-PDDT changes the absorption intensity and induces a redshift to characteristic peaks. CNT hybrid features have appeared on the surface morphology as verified by atomic force microscopic images. The concentration of additive was optimized at 0.5 wt% to obtain the highest efficiency. Doping with this concentration of CNT-graft-PDDT led to 380% power conversion efficiency improvement by enhancement of short-circuit current density (Jsc) from 5.12 to 11.98 mA/cm2, open-circuit voltage (Voc) from 0.6 to 0.66 V, and fill factor from 0.41 to 0.62 in comparison with a reference cell. The photophysics of hybrid systems were also studied by means of the electrochemical impedance spectroscopy as well as Voc and Jsc dependent on the light intensity.
关键词： Organic photovoltaic cells,Charge carrier recombination,Energy conversion,CNT-graft-PDDT
更新于2025-09-23 15:21:01
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Thin-Film Solar Cells
摘要： Copper-indium-gallium-diselenide (CIGS) thin-film solar cells suffer from high recombination losses at the back contact and parasitic absorption in the front-contact layers. Dielectric passivation layers overcome these limitations and enable an efficient control over interface recombination, which becomes increasingly relevant as thin-film solar cells increase in efficiency and become thinner to reduce the consumption of precious resources. We present the optoelectronic and chemical interface properties of oxide-based passivation layers deposited by atomic layer deposition on CIGS. A suitable postdeposition annealing removes detrimental interface defects and leads to restructuring and oxidation of the CIGS surface. The optoelectronic interface properties are very similar for different passivation approaches, demonstrating that an efficient suppression of interface states is possible independent of the metal used in the passivating oxide. If aluminum oxide (Al2O3) is used as the passivation layer we confirm an additional field-effect passivation due to interface charges, resulting in an efficient interface passivation superior to that of a state-of-the-art cadmium-sulfide (CdS) buffer layer. Based on this chemical interface model we present a full-area rear-interface passivation layer without any contact patterning, resulting in a 1% absolute efficiency gain compared to a standard molybdenum back contact.
关键词： CIGS,CdS,atomic layer deposition,oxidation,thin-film solar cells,recombination losses,Al2O3,interface passivation
更新于2025-09-23 15:21:01
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Photoluminescencea??Based Characterization of Halide Perovskites for Photovoltaics
摘要： Photoluminescence spectroscopy is a widely applied characterization technique for semiconductor materials in general and halide perovskite solar cell materials in particular. It can give direct information on the recombination kinetics and processes as well as the internal electrochemical potential of free charge carriers in single semiconductor layers, layer stacks with transport layers, and complete solar cells. The correct evaluation and interpretation of photoluminescence requires the consideration of proper excitation conditions, calibration and application of the appropriate approximations to the rather complex theory, which includes radiative recombination, non-radiative recombination, interface recombination, charge transfer, and photon recycling. In this article, an overview is given of the theory and application to specific halide perovskite compositions, illustrating the variables that should be considered when applying photoluminescence analysis in these materials.
关键词： halide perovskites,photoluminescence,photovoltaics,charge carriers,recombination kinetics
更新于2025-09-23 15:21:01
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Understanding Temperature-Dependent Charge Extraction and Trapping in Perovskite Solar Cells
摘要： Understanding the factors that limit the performance of perovskite solar cells (PSCs) can be enriched by detailed temperature (T)-dependent studies. Based on p-i-n type PSCs with prototype methylammonium lead triiodide (MAPbI3) perovskite absorbers, T-dependent photovoltaic properties are explored and negative T-coefficients for the three device parameters (VOC, JSC, and FF) are observed within a wide low T-range, leading to a maximum power conversion efficiency (PCE) of 21.4% with an impressive fill factor (FF) approaching 82% at 220 K. These T-behaviors are explained by the enhanced interfacial charge transfer, reduced charge trapping with suppressed nonradiative recombination and narrowed optical bandgap at lower T. By comparing the T-dependent device behaviors based on MAPbI3 devices containing a PASP passivation layer, enhanced PCE at room temperature is observed but different tendencies showing attenuating T-dependencies of JSC and FF, which eventually leads to nearly T-invariable PCEs. These results indicate that charge extraction with the utilized all-organic charge transporting layers is not a limiting factor for low-T device operation, meanwhile the trap passivation layer of choice can play a role in the T-dependent photovoltaic properties and thus needs to be considered for PSCs operating in a temperature-variable environment.
关键词： temperature dependence,charge trapping,recombination,charge extraction,passivation layer
更新于2025-09-23 15:21:01
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Enhancing Perovskite Solar Cell Performance through Femtosecond Laser Polishing
摘要： Nonradiative recombination loss is a key process that determines the performance of perovskite solar cells, and how to control it is significant for the research and development of perovskites. Generally, traditional chemical modification/passivation methods are complicated and prone to secondary contamination. Here, we demonstrate femtosecond (fs) laser polishing as a promising technique to ameliorate the surface of perovskite films, to reduce nonradiative recombination loss and improve solar cell performance. The high-intensity fs laser pulses can remove around 20-nm thick perovskite top-layer through ionization process, help to decrease the grain boundary density and enlarge the grain size of perovskite films after recrystallization. We believe that fs laser polishing is a time-effective and highly precise technique which is suitable for large-scaled device production, thus will trigger more applications in optoelectronics.
关键词： femtosecond lasers,perovskites,recombination,passivation,solar cells
更新于2025-09-23 15:21:01
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Research and Modeling of Photovoltaic Array Channel Noise Characteristics
摘要： The photovoltaic array can be used as a medium for carrier communication to realize monitoring of photovoltaic components. Photovoltaic array channel noise, especially the pulse-type noise therein, seriously interferes carrier communication, so it is necessary to grasp the characteristics of the photovoltaic array channel noise. Photovoltaic array channel noise modeling is a key process when conducting anti-noise immunity tests of monitoring equipment. Based on the time-domain waveform of photovoltaic series channel noise which is measured in a photovoltaic power station, this paper proposes a photovoltaic array noise modeling method of Wavelet Peak-Type Markov chain, and studies the in?uence on modeling accuracy when different mother wavelets are adopted for modeling. From the simulation results, root mean square errors of the predicted output for Haar, Biorthogonal and Daubechies wavelet-based function modeling case are 0.9614 V, 1.4915 V and 0.7928 V, respectively, validating that Daubechies wavelet-based function is the best wavelet-based function of modeling. In the case that the peak of original noise reaches 20 V, the predicted mean absolute error of this model is only 0.4926 V, which not only veri?es the applicability of the Wavelet Peak-Type Markov chain model to the photovoltaic array channel noise, but also veri?es the applicability to the pulse-type noise.
关键词： photovoltaic array channel noise,noise characteristics and modeling,wavelet packet decomposition and recombination,Peak-Type Markov chain
更新于2025-09-23 15:21:01
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Effect of Doping on the Luminescent Properties of LED Heterostructures with Quantum Wells
摘要： It is established that the model of interband radiative recombination in a semiconductor under bipolar injection of charge carriers, in which the recombination rate is described by the product of the total charge carrier concentrations, does not take into account the imbalance in the concentrations of recombining particles physically existing during doping. To calculate the number of electron-hole pair recombination events taking into account the difference in the concentrations of recombining particles, it is proposed to use the calculation of the reciprocal sum of the reciprocal concentrations using the participation functions. It is shown that at such a description of the number of recombination events, an increase in the doping impurity concentration reduces the number of events, but leaves the radiative recombination time unchanged at any injection level.
关键词： emission of radiation,radiative recombination rate,participation functions
更新于2025-09-23 15:21:01
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The influence of bilateral environment of dyed-TiO2/electrolyte interface on detailed recombination process during the a??maturea?? period of sensitized solar cell
摘要： The complete dye-sensitized solar cell (DSC) life cycle includes three stages: “mature” period, stability period and degradation period. However, during the DSC performance adjustment period, considering the in?uence of both sides of the dyed-TiO2/electrolyte interface on the electron recombination process is still blank. In this paper, the effects of the environment on both sides of the interface between TiO2 and electrolyte during the DSC performance adjustment on the electron recombination process are studied. The results show that the performance adjustment of DSC is greatly in?uenced by the chemical environment of electrolyte. The ?lm microstructures have a certain in?uence on the electron recombination process during the performance adjustment. During the performance adjustment period of DSC, the adjustment of quasi-Fermi level is more complicated under the condition of weak light than under the condition of strong light. The results of this paper are signi?cant for studying complex systems of DSC, understanding the device working mechanism and improving the cell ef?ciency.
关键词： Performance adjustment period,Electron recombination,TiO2 ?lm,Dye-sensitized solar cell,Electrolyte
更新于2025-09-23 15:21:01
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Distinctive features of diffusion-controlled radiation defect recombination in stoichiometric magnesium aluminate spinel single crystals and transparent polycrystalline ceramics
摘要： MgAl2O4 spinel is important optical material for harsh radiation environment and other important applications. the kinetics of thermal annealing of the basic electron (F, F+) and hole (V) centers in stoichiometric MgAl2O4 spinel irradiated by fast neutrons and protons is analyzed in terms of diffusion-controlled bimolecular reactions. properties of MgAl2O4 single crystals and optical polycrystalline ceramics are compared. it is demonstrated that both transparent ceramics and single crystals, as well as different types of irradiation show qualitatively similar kinetics, but the effective migration energy Ea and pre-exponent D0 are strongly correlated. Such correlation is discussed in terms of the so-called Meyer-Neldel rule known in chemical kinetics of condensed matter. The results for the irradiated spinel are compared with those for sapphire, MgO and other radiation-resistant materials.
关键词： diffusion-controlled bimolecular reactions,MgAl2O4 spinel,thermal annealing,Meyer-Neldel rule,radiation defect recombination
更新于2025-09-23 15:21:01
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Chemistry of ternary monocarboxyterpyridine-bipyridine-trimercaptotriazine ruthenium complexes and application in dye sensitized solar cells
摘要： The synthesis of the [RuII(Hmctpy)(H2O)(Cl2)], [RuII(Hmctpy)(dmbpy)Cl]Cl and [RuII(Hmctpy)(dmbpy)(H3tmt)](PF6)2 complexes (mctpy = monocarboxyterpyridine, dmbpy = dimethylbipyridine, tmt = trimercaptotriazine) was carried out based on a vectorial design for energy transfer in dye sensitized solar cells (DSSC). The [RuII(mctpy)(dmbpy)(Hxtmt)]n complexes were fully characterized and the electrochemical and absorption/emission properties corroborated their potentially as TiO2 photosensitizing agents. However, the observed current density and open circuit voltage were rather small, imparting a low efficiency for the assembled DSSCs. The results indicated a unexpected contribution of the charge recombination effects at the electrode surface. Such effects increased with the number of deprotonated groups in the tmt ligand as they interact with the nanocrystalline TiO2 surface, capturing electrons from the conduction band.
关键词： Ruthenium dyes,Carboxypolyimine dyes,Photoelectrochemistry,Charge recombination,Trimercaptotriazine dyes
更新于2025-09-23 15:21:01