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Impact of Temperature Dependent Hydration Water on Perovskite Solar Cells
摘要： Water effect on perovskite solar cells has received growing interest in recent years. A widely accepted view is that moderate water content induces the formation of hydrate phase which enhances the recrystallization of the perovskite. However, the underlying factors which influence the formation of hydrate phase have yet to be investigated. Herein, by controlling the annealing temperature, it is demonstrated that 60 ℃ is the most suitable temperature for the formation of hydrated perovskite. After further annealing at 120 ℃, the resulting perovskite film reveals enhanced crystallinity with a more uniform morphology, contributing to device efficiency above 20%. In addition, the water effect on different types of perovskites is studied and it is concluded that the formation of hydrated perovskite is mainly determined by the cations of the perovskite itself. The findings in this work elucidate the conditions for the formation of hydrated perovskite, contributing to the fabrication of highly efficient perovskite solar cells.
关键词： annealing temperature,perovskite solar cell,cation,water effect
更新于2025-09-11 14:15:04
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Efficient non-fullerene polymer solar cells enabled by side-chain conjugated thieno[3,4-c]pyrrole-4,6-dione-based polymer and small molecular acceptors
摘要： The application of non-fullerene (NF) acceptors in bulk-heterojunction (BHJ) polymer solar cells (PSCs) is a promising approach to overcome the inherent drawbacks of fullerene derivatives-based acceptors. In PSCs, complementary absorption as well as matched molecular energy levels between the low bandgap acceptor-donor-acceptor (A-D-A) small molecular acceptor and medium/wide bandgap polymer donor is crucial to achieve high power conversion efficiency (PCE). Alternating polymers based on benzodithiophene (BDT) electron-donating segment and thieno[3,4-c]pyrrole-4,6-dione (TPD) electron-withdrawing segment own medium bandgap and low-lying highest occupied molecular orbital (HOMO) energy level, leading to presentable photovoltaic properties with fullerene derivatives. To probe into the performances of TPD-based polymers in NF-PSCs, two TPD-based polymers containing alkoxy or alkylthienyl modified benzo[1,2-b:4,5-b′]dithiophene (BDT) were synthesized and adopted as electron-donors and blended with A-D-A-type electron-acceptor 2,2′-[[6,6,12,12-tetrakis(4-hexylphenyl)-s-indacenodithieno[3,2-b]thiophene]methylidyne(3-oxo-1H-indene-2,1(3H)-diylidene)]]bis(propanedinitrile) (ITIC) to fabricate the corresponding photovoltaic devices. The two-dimensional conjugated polymer PBDTT-TPD shows enhanced extinction coefficient, deeper HOMO energy level and better hole transport performance, resulting in improved PCE of 6.17%. To further boost the performances of the polymers, a small molecular acceptor 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl) bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC) with down-shifted energy level was also used to blend with the two polymers in PSCs. Despite the open-circuit voltage (VOC) of the PBDTT-TPD:IDIC-based device is slightly decreased, the short-circuit current density (JSC) and fill factor (FF) are simultaneously improved, yielding an promising PCE of 7.15%. These results indicate that two-dimensional conjugated TPD-based polymers can be potential application as medium bandgap polymeric donor to match with small molecular acceptors having suitable molecular energy levels to get high efficiency in PSCs.
关键词： Non-fullerene acceptors,Thieno[3,4-c]pyrrole-4,6-dione,Energy level offsets,Polymer solar cells,Thermal annealing
更新于2025-09-11 14:15:04
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Fields of application for laser beam polishing of optical glasses
摘要： Conventional manufacturing of freeform optics is expensive and elaborate. The laser beam as a polishing tool offers the possibility to produce optical surfaces fast and effective. The aim of new research on laser beam polishing of optical glasses is to achieve a polished surface finish irrespective of the surface geometrics. The carbon dioxide laser is applied to process pre-machined specimen with different roughness’s. During the polishing process an infrared camera is necessary to monitor the temperature on the surface. An annealing process reduces the process-related tensions. In addition, the cleaning process is investigated to minimize the surface damages. To characterize the surface topographic a white-light interferometer and a stylus instrument are applied. Laser beam polishing of minerals glasses such as N-BK7?, BF33? and fused silica enables surface roughness of less than Ra < 5 nm by form maintenance. By means of self-design setup, the adaption of laser beam polishing on glass cylinders, lenses or freeform is possible. As a result a parallel laser beam with a diameter of 12.65 mm is applied to process tilted surfaces up to 45°. With a laser parameter modulation, the angle-dependent absorption depending on the intensity of the laser radiation is considered.
关键词： white-light interferometer,surface finish,optical glasses,annealing process,cleaning process,infrared camera,carbon dioxide laser,laser beam polishing,stylus instrument
更新于2025-09-11 14:15:04
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[IEEE 2019 26th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) - Kyoto, Japan (2019.7.2-2019.7.5)] 2019 26th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) - PEDOT:PSS Transparent Electrode for ITO-Free Polymer:Fullerene Bulk-Heterojunction Organic Solar Cells
摘要： Conducting poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films have high potential as flexible transparent conductive electrodes in various devices. In this study, two simple robust methanol-based treatment methods, namely, dipping process (DP) and solvent vapor annealing (SVA), were used to improve the electrical conductivity of PEDOT:PSS films in order to make them suitable as electrodes in organic solar cells (OSCs). Then, the characteristics of the methanol-treated PEDOT:PSS films were investigated. After the methanol treatments, the sheet resistance of the PEDOT:PSS films (ca. 100 ?/Sq) were improved by more than 200 times, and the work function (~5.0 eV) was nearly unchanged in both methods. Two completely different possible origins of the improved conductivity of the methanol-treated PEDOT:PSS films were addressed for DP and SVA approaches. Both methods were suitable for preparing methanol-treated PEDOT:PSS films that can be used as anodes for polymer–fullerene-based OSCs. The photovoltaic performance of the modified PEDOT:PSS-based devices was comparable to that of indium tin oxide (ITO)-based devices, thus demonstrating their practicality. The methanol-treated PEDOT:PSS films show great potential as flexible transparent conductive electrodes for ITO-free and metal-free devices.
关键词： dipping process,solvent vapor annealing,organic solar cells,methanol treatment,transparent electrode,PEDOT:PSS
更新于2025-09-11 14:15:04
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Filterless Polarization‐Sensitive 2D Perovskite Narrowband Photodetectors
摘要： An important factor for the high performance of light-harvesting devices is the presence of surface trappings. Therefore, understanding and controlling the carrier recombination of the organic?inorganic hybrid perovskite surface is critical for the device design and optimization. Here, we report the use of aluminum zinc oxide (AZO) as the anode to construct a p?n junction structure MAPbBr3 nuclear radiation detector. The AZO/MAPbBr3/Au detector can tolerate an electrical field of 500 V·cm?1 and exhibit a very low leakage current of ～9 nA, which is 1 order of magnitude lower than that of the standard ohmic contact device. The interface state density of AZO/MAPbBr3 contact was reduced from 2.17 × 1010 to 8.7 × 108 cm?2 by annealing at 100 °C under an Ar atmosphere. Consequently, a photocurrent to dark current ratio of 190 was realized when exposed to a green light-emitting diode with a wavelength of 520 nm (～200 mW·cm?2). Simultaneously, a high X-ray sensitivity of ～529 μC·Gyair?1 cm?2 was achieved under 80 kVp X-ray at an electric field of 50 V·cm?1. These results demonstrate the use of surface engineering to further optimize the performance of MAPbBr3 detectors, which have many potential applications in medical and security detection with low radiation dose brought to the human body.
关键词： p?n junction,X-ray detector,interface state density,MAPbBr3 PSC,annealing
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || XTEM observations revealing high diffusivity and Ge segregation in UV laser pulse annealed SiGeO and GeTiO amorphous films
摘要： XTEM observations revealing high diffusivity and Ge segregation in UV laser pulse annealed SiGeO and GeTiO amorphous films
关键词： laser annealing,thin films,nanoparticles,Ge diffusion
更新于2025-09-11 14:15:04
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Postannealed Structural Relaxation and Phase Evolution of Quaternary Alloy BeMgZnO
摘要： The thermal stability of quaternary alloy BeMgZnO was investigated in this study. When a Be0.09Mg0.19Zn0.72O alloy film was annealed, structural relaxation and reconstruction of the film layers were found at 600, 700, and 800 °C. Be atoms were found to gradually diffuse out from the host lattice, and Mg atoms were still maintained. As a result, a mixed-phase alloy containing BeO and MgxZn1?xO was continuously generated. Correspondingly, the bandgap of Be0.09Mg0.19Zn0.72O reduced because of the diffusion of Be atoms. Hence, the thermodynamic solubility of BeO in ZnO and MgO was demonstrated to be relatively low. Additionally, the aging effect caused by a higher annealing temperature is more effective than that caused by a lower annealing temperature for a longer time. Due to the improvement of crystal quality, an MSM interdigital structure photodetector based on the 800 °C annealed sample was fabricated and revealed a strong response to the UV light. Our finding provides a new understanding of the ultrawide bandgap quaternary alloy BeMgZnO and contributes to a significant step toward its practical applications.
关键词： bandgap,photodetector,Be diffusion,BeMgZnO,thermal annealing,structural relaxation
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing THE 7TH INTERNATIONAL CONFERENCE ON APPLIED SCIENCE AND TECHNOLOGY (ICAST 2019) - Karbala City, Iraq (27–28 March 2019)] THE 7TH INTERNATIONAL CONFERENCE ON APPLIED SCIENCE AND TECHNOLOGY (ICAST 2019) - Structure, morphology and optical properties of thermally evaporated Cu2S thin films annealed at different temperatures
摘要： In the present work the preparation of Cu2S alloy was done throughout mixing the sulphur and copper elements according to the proper atomic weight and then put in an evacuated quartz ampoule which then sealed and heated at 1273 K for five hours and left to cool. Thin films from Cu2S powder thicknesses of ~300nm were prepared by thermal evaporation technique on a glass substrate and under vacuum of 10-5 mbar with rate of deposition 25nm/sec. The prepared thin films subjected to heat treatment at different temperatures(300, 373 , 473 and 573 K)for half an hour. The structures of Cu2S powder and films have been studied by X–ray diffraction technique. The result reveals that the prepared alloy has cubic structure and coincides with slandered cards while the prepared thin films have amorphous structure. The optical measurement shows that the Cu2S films have direct and indirect energy gap energy gap (Eg opt) for allowed transition. The energy gap (Eg opt) increases slightly with the increase annealing temperature and retune to increase with further increases of annealing temperature. The energy gap (Eg opt) increases from 2.55 to 2.6 eV and then decreases. The transmittance and optical constants such as refractive index (n), extinction coefficient (k) and dielectric constant (εr, εi) have been calculated. The optical constants decrease in the first and then return to increase with annealing temperature.
关键词： Cu2S thin films,optical properties,structural morphology,thermal evaporation,annealing temperature
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Low-temperature silicon surface passivation for bulk lifetime studies based on Corona-charged Al2O3
摘要： Bulk lifetime studies of crystalline silicon wafers, e.g. with the aim of studying the light-induced degradation and regeneration behavior, require low-temperature surface passivation schemes that do not alter the silicon bulk properties, e.g. through hydrogenation. Aluminum oxide (Al2O3) can provide an excellent and stable surface passivation, however, in order to achieve the best possible surface passivation, an annealing step at ~400°C is typically required, which has been found to alter the bulk properties of some silicon materials. Hence, in this contribution we examine the possibility of passivating the silicon surface using Al2O3 layers that have seen a much lower thermal budget. We demonstrate that we are able to achieve an excellent silicon surface passivation using atomic-layer-deposited Al2O3 with measured effective surface recombination velocities Seff as low as 1.3 cm/s without exceeding a temperature of 250°C. We are able to achieve such excellent low-temperature passivation by applying a post-deposition annealing step at 250°C in combination with the deposition of negative Corona charges on the Al2O3 surface. For samples annealed at only 220°C, we still reach very low Seff values of 2 cm/s after deposition of negative Corona charges. We demonstrate that the Corona-charged low-temperature Al2O3 passivation shows only a slight degradation from an Seff of 1.6 cm/s to an Seff of 5 cm/s after 218 days of storage. Even without any post-deposition anneal and only negative Corona charges deposited, we achieve stable Seff values of 15 cm/s. As an alternative to Corona charging, a short exposure to intense UV light (λ = 395 nm) also significantly improves the surface passivation quality of low-temperature-annealed Al2O3-passivated silicon samples. However, the best surface passivation for the latter method is limited to an Seff value of 6.6 cm/s, which is still quite reasonable for bulk lifetime studies.
关键词： bulk lifetime studies,Al2O3,Corona charging,silicon surface passivation,low-temperature annealing
更新于2025-09-11 14:15:04
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Reversible PL Tuning by Defect Passivation via Laser Irradiation on Aged Monolayer MoS2
摘要： Atomically thin (1L) MoS2 emerged as a direct band gap semiconductor with potential optical applications. The photoluminescence (PL) of 1L-MoS2 degrades due to aging related defect formation. The passivation of these defects leads to substantial improvement in optical properties. Here we report the enhancement of PL on aged 1L-MoS2 by laser treatment. Using photoluminescence and Raman spectroscopy in a controlled gas environment, we show the enhancement is associated with efficient adsorption of oxygen on existing sulfur vacancies preceded by removal of adsorbates from the sample’s surface. Oxygen adsorption depletes negative charges, resulting in suppression of trions and improved neutral exciton recombination. The result is a 6-8 fold increase in PL emission. The laser treatment in this work does not cause any measurable damage to the sample as verified by Raman spectroscopy, which is important for practical applications. Surprisingly, the observed PL enhancement is reversible by both vacuum and ultrafast femtosecond excitation. While the former approach allows switching a designed micro pattern on the sample ON and OFF, the latte provides a controllable mean for accurate PL tuning, which is highly desirable for optoelectronic and gas sensing applications.
关键词： Raman,Exciton,Laser Annealing,Oxygen,Photoluminescence,Reversible Defect passivation,MoS2
更新于2025-09-11 14:15:04