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Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications
摘要： In this work, we utilize a bottom-up approach to synthesize nitrogen self-doped graphene quantum dots (NGQDs) from a single glucosamine precursor via an eco-friendly microwave-assisted hydrothermal method. Structural and optical properties of as-produced NGQDs are further modified using controlled ozone treatment. Ozone-treated NGQDs (Oz-NGQDs) are reduced in size to 5.5 nm with clear changes in the lattice structure and ID/IG Raman ratios due to the introduction/alteration of oxygen-containing functional groups detected by Fourier-transform infrared (FTIR) spectrometer and further verified by energy dispersive X-ray spectroscopy (EDX) showing increased atomic/weight percentage of oxygen atoms. Along with structural modifications, GQDs experience decrease in ultraviolet–visible (UV–vis) absorption coupled with progressive enhancement of visible (up to 16 min treatment) and near-infrared (NIR) (up to 45 min treatment) fluorescence. This allows fine-tuning optical properties of NGQDs for solar cell applications yielding controlled emission increase, while controlled emission quenching was achieved by either blue laser or thermal treatment. Optimized Oz-NGQDs were further used to form a photoactive layer of solar cells with a maximum efficiency of 2.64% providing a 6-fold enhancement over untreated NGQD devices and a 3-fold increase in fill factor/current density. This study suggests simple routes to alter and optimize optical properties of scalably produced NGQDs to boost the photovoltaic performance of solar cells.
关键词： photovoltaics,optical properties,ozone treatment,nitrogen-doped graphene quantum dots,solar cells
更新于2025-11-19 16:56:42
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<i>In Situ</i> 2D Perovskite Formation and the Impact of the 2D/3D Structures on Performance and Stability of Perovskite Solar Cells
摘要： Hybrid organic and inorganic perovskite solar cells suffer from the lack of long-term stability and this negatively impacts the widespread application of this emerging and promising photovoltaic technology. In this work, aiming to increase the stability of perovskite films based on CH3NH3PbI3 and to deep understand the formation of 2D structures, solutions of alkylammonium chlorides containing 8, 10 and 12 carbons were introduced during the spin-coating on the surface of 3D perovskite films leading to the in situ formation of 2D structures. It was possible to identify the chemical formulae of some 2D structures formed by XRD and UV-Vis analysis of the modified films. Interestingly, the increase in the stability of the CH3NH3PbI3 films due to the formation of a 2D+3D perovskite network was only possible in planar TiO2 substrates. The increase on stability of the CH3NH3PbI3 films follows the surfactant molecule order: octylammonium (8C) > decylammonium (10C) > dodecylammonium (12C) chlorides > standard. We observed an increase of 17.6 % in the lifetime of the devices assembled with modified perovskite film compared to our standard device, which is directly linked to the improvement of the charge carrier lifetimes obtained from Time-Correlated Single Photon Counting (TCSPC) measurements.
关键词： Energy Conversion,Photovoltaics,Stability,2D perovskite,Perovskite Solar Cell
更新于2025-11-19 16:56:35
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RbF post deposition treatment for narrow bandgap Cu(In,Ga)Se2 solar cells
摘要： Multi-junction solar cells are known to have a considerably increased efficiency potential over their typical single junction counterparts. In order to produce low cost and lightweight multi-junction devices, the availability of suitable narrow (<1.1 eV) bandgap bottom cells is paramount. A possible absorber for such a bottom cell is the Cu(In,Ga)Se2 (CIGS) compound semiconductor, one of the most efficient thin film materials to date. In this contribution we report on the RbF post deposition treatment of narrow bandgap CIGS absorbers grown with a single bandgap grading approach. We discuss the necessary deposition conditions and the observed improvements on solar cells performance. A certified record efficiency of 18.0 % for an absorber with 1.00 eV optoelectronic bandgap is presented and its suitability for perovskite/CIGS tandem devices is shown.
关键词： Post deposition treatment,Narrow bandgap,Tandem solar cells,Thin film solar cells,photovoltaics,Rubidium fluoride,Copper indium gallium selenide
更新于2025-11-14 17:28:48
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Manufacturing of All Inkjet-Printed Organic Photovoltaic Cell Arrays and Evaluating their Suitability for Flexible Electronics
摘要： The generation of electrical energy depending on renewable sources is rapidly growing and gaining serious attention due to its green sustainability. With fewer adverse impacts on the environment, the sun is considered as a nearly infinite source of renewable energy in the production of electrical energy using photovoltaic devices. On the other end, organic photovoltaic (OPV) is the class of solar cells that offers several advantages such as mechanical flexibility, solution processability, environmental friendliness, and being lightweight. In this research, we demonstrate the manufacturing route for printed OPV device arrays based on conventional architecture and using inkjet printing technology over an industrial platform. Inkjet technology is presently considered to be one of the most matured digital manufacturing technologies because it offers inherent additive nature and last stage customization flexibility (if the main goal is to obtain custom design devices). In this research paper, commercially available electronically functional inks were carefully selected and then implemented to show the importance of compatibility between OPV material stacks and the device architecture. One of the main outcomes of this work is that the manufacturing of the OPV devices was accomplished using inkjet technology in massive numbers ranging up to 1500 containing different device sizes, all of which were deposited on a flexible polymeric film and under normal atmospheric conditions. In this investigation, it was found that with a set of correct functional materials and architecture, a manufacturing yield of more than 85% could be accomplished, which would reflect high manufacturing repeatability, deposition accuracy, and processability of the inkjet technology.
关键词： inkjet technology,flexible electronics,organic photovoltaics,Indium Tin Oxide (ITO) free solar cells
更新于2025-11-14 17:28:48
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Thinning ferroelectric films for high-efficiency photovoltaics based on the Schottky barrier effect
摘要： Achieving high power conversion efficiencies (PCEs) in ferroelectric photovoltaics (PVs) is a longstanding challenge. Although recently ferroelectric thick films, composite films, and bulk crystals have all been demonstrated to exhibit PCEs >1%, these systems still suffer from severe recombination because of the fundamentally low conductivities of ferroelectrics. Further improvement of PCEs may therefore rely on thickness reduction if the reduced recombination could overcompensate for the loss in light absorption. Here, a PCE of up to 2.49% (under 365-nm ultraviolet illumination) was demonstrated in a 12-nm Pb(Zr0.2Ti0.8)O3 (PZT) ultrathin film. The strategy to realize such a high PCE consists of reducing the film thickness to be comparable with the depletion width, which can simultaneously suppress recombination and lower the series resistance. The basis of our strategy lies in the fact that the PV effect originates from the interfacial Schottky barriers, which is revealed by measuring and modeling the thickness-dependent PV characteristics. In addition, the Schottky barrier parameters (particularly the depletion width) are evaluated by investigating the thickness-dependent ferroelectric, dielectric and conduction properties. Our study therefore provides an effective strategy to obtain high-efficiency ferroelectric PVs and demonstrates the great potential of ferroelectrics for use in ultrathin-film PV devices.
关键词： power conversion efficiency,Schottky barrier effect,ferroelectric photovoltaics,PZT ultrathin film,depletion width
更新于2025-11-14 17:28:48
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Aluminum-Doped Zinc Oxide as Front Electrode for Rear Emitter Silicon Heterojunction Solar Cells with High Efficiency
摘要： Transparent conductive oxide (TCO) layers of aluminum-doped zinc oxide (ZnO:Al) were investigated as a potential replacement of indium tin oxide (ITO) for the front contact in silicon heterojunction (SHJ) solar cells in the rear emitter configuration. It was found that ZnO:Al can be tuned to yield cell performance almost at the same level as ITO with a power conversion efficiency of 22.6% and 22.8%, respectively. The main reason for the slight underperformance of ZnO:Al compared to ITO was found to be a higher contact resistivity between this material and the silver grid on the front side. An entirely indium-free SHJ solar cell, replacing the ITO on the rear side by ZnO:Al as well, reached a power conversion efficiency of 22.5%.
关键词： photovoltaics,silicon heterojunction,rear emitter,transparent conductive oxide
更新于2025-11-14 15:25:21
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All-Thin-Film Tandem Cells Based on Liquid Phase Crystallized Silicon and Perovskites
摘要： Combining the emerging perovskite solar cell technology with existing silicon approaches in a tandem cell design offers the possibility for new low-cost high-performance devices. In this study, the potential of liquid phase crystallized silicon (LPC-Si) solar cells as a bottom cell in an all-thin-film tandem device is investigated. By optimizing the current output of a four terminal tandem using optical simulations and state-of-the-art electrical properties of the top and bottom cells, we show that an efficiency of 23.3% can be reached, where 7.2% are attributed to the LPC-Si bottom cell. Including the potential of future developments of both sub cells, efficiencies of over 28% are estimated. Electrical and optical measurements of the bottom cell are performed by attaching a perovskite and a cutoff filter to the front side of the interdigitated back contacted LPC-Si cells. The measurements using a cutoff filter show a high impact of the filtered incident light spectrum on the open circuit voltage of the LPC-Si cell. A comparison of the simulated and measured absorptance shows that especially the optical properties of the transparent conductive oxides and recombination losses in the LPC-Si cause high current losses. Combining the measured data of the filtered LPC-Si cells and the semitransparent perovskite cells, yields a realistic estimation for the efficiency of a state-of-the-art four-terminal tandem device of 19.3%.
关键词： tandem devices,Liquid phase crystallization (LPC),perovskite solar cells,thin film photovoltaics
更新于2025-11-14 15:25:21
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Enabling low voltage losses and high photocurrent in fullerene-free organic photovoltaics
摘要： Despite significant development recently, improving the power conversion efficiency of organic photovoltaics (OPVs) is still an ongoing challenge to overcome. One of the prerequisites to achieving this goal is to enable efficient charge separation and small voltage losses at the same time. In this work, a facile synthetic strategy is reported, where optoelectronic properties are delicately tuned by the introduction of electron-deficient-core-based fused structure into non-fullerene acceptors. Both devices exhibited a low voltage loss of 0.57 V and high short-circuit current density of 22.0 mA cm?2, resulting in high power conversion efficiencies of over 13.4%. These unconventional electron-deficient-core-based non-fullerene acceptors with near-infrared absorption lead to low non-radiative recombination losses in the resulting organic photovoltaics, contributing to a certified high power conversion efficiency of 12.6%.
关键词： non-fullerene acceptors,power conversion efficiency,voltage losses,charge separation,organic photovoltaics
更新于2025-11-14 15:18:02
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Growth and characterization of hybrid (HoGO/P3HT) graphene-based nanostructures for photovoltaic (PV) applications.
摘要： Herein, we present a comparative study between nanostructures of poly(3-hexylthiophene) (P3HT), Holmium-Graphene Oxide (HoGO) nanocomposite and hybrid HoGO/P3HT thin-film nanostructures in terms of structural, morphological and spectroscopic properties. Specifically, the graphene based GO nanostructure was functionalized with rear earth ion Ho(III) to improve its mobility. Furthermore, semiconducting P3HT nanostructure was successfully grown with HoGO nanocomposite creating hybrid HoGO/P3HT nanostructure for energy materials. The nanostructures were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), (FTIR) and UV/VIS/NIR spectroscopy. The interaction between HoGO and HoGO/P3HT nanostructures is evidenced through substantial variations in nanoparticle morphologies. FTIR results provided the evidence of the presence of different types of carbon functionalities in the nanostructures. From the absorption spectra, growth of hybrid HoGO/P3HT nanostructure broadened the absorbance with a slight decrease in %. These nanostructures open a promising direction on growth of hybrids for photovoltaic applications because of their interesting optical properties.
关键词： nanostructures,Hybrid,nanocomposite,thin-film,photovoltaics
更新于2025-10-22 19:40:53
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Surface Plasmon Resonance Enhancement of PbS Quantum Dot-Sensitized Solar Cells
摘要： Lead sulfide (PbS)-sensitized quantum dot solar cells (QDSC) were fabricated using TiO2 and TiO2–Au plasmonic nanocomposite films by successive ionic layer adsorption and reaction (SILAR) method. The average size of gold nanoparticles (GNPs) used for fabricating nanocomposite films was ~ 15 nm. Thin plasmonic QDSC, with a film thickness of 10 μm, showed an increase of ~ 11% in photocurrent and ~ 6% in overall energy conversion efficiency compared to the device without GNPs. The improved performance of QDSCs is attributed to the increased absorption due to the plasmonic near-field effects of the incorporated GNPs. High-efficiency PbS/CdS-co-sensitized thick cells with 16 μm bilayer TiO2 also showed improvement in photocurrent and efficiency. The results show that the plasmonic-enhanced absorption can be used to augment efficiency of QDSC devices in much the same fashion as that of dye-sensitized solar cells.
关键词： Gold nanoparticles,Quantum dot-sensitized solar cells,Plasmonics,Photovoltaics
更新于2025-10-22 19:40:53