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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Test-Based Modeling of Photovoltaic Inverter Impact on Distribution Systems
摘要： AC voltage regulation is required in both the domestic and industrial sectors to avoid undesired effects from random voltage variations of the power supply. The paper introduces an ac voltage stabilizer/converter (ACVS) that is based on a controllable autotransformer technology. The proposed ACVS offers a specified strategy of voltage regulation, less harmonics, and low cost. The paper explains the operating principle of the ACVS and derives its nonlinear mathematical model. To ensure the desired performance of the ACVS while it is subject to uncertain input voltage and load variations, an optimal control strategy is designed. It is achieved via transforming the ACVS model extending with fictive axis emulation into a rotating reference frame and the linearization of the model via specific orientation of the reference frame and introducing a linear control action. Operation of the ACVS is simulated under different disturbances due to load and grid voltage changes, and compared to voltage stabilization with application of I and PI controllers. Experimental results are presented to demonstrate the voltage regulation technology.
关键词： AC–AC power conversion,electric variables control,linear-quadratic control,power quality,voltage control
更新于2025-09-23 15:19:57
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Over 15% Efficiency Polymer Solar Cells Enabled by Conformation Tuning of Newly Designed Asymmetric Smalla??Molecule Acceptors
摘要： The prosperous period of polymer solar cells (PSCs) has witnessed great progress in molecule design methods to promote power conversion efficiency (PCE). Designing asymmetric structures has been proved effective in tuning energy level and morphology, which has drawn strong attention from the PSC community. Two hepta-ring and octa-ring asymmetric small molecular acceptors (SMAs) (IDTP-4F and IDTTP-4F) with S-shape and C-shape confirmations are developed to study the relationship between conformation shapes and PSC efficiencies. The similarity of absorption and energy levels between two SMAs makes the conformation a single variable. Additionally, three wide-bandgap polymer donors (PM6, S1, and PM7) are chosen to prove the universality of the relationship between conformation and photovoltaic performance. Consequently, the champion PCE afforded by PM7: IDTP-4F is as high as 15.2% while that of PM7: IDTTP-4F is 13.8%. Moreover, the S-shape IDTP-4F performs obviously better than their IDTTP-4F counterparts in PSCs regardless of the polymer donors, which confirms that S-shape conformation performs better than the C-shape one. This work provides an insight into how conformations of asymmetric SMAs affect PCEs, specific functions of utilizing different polymer donors to finely tune the active-layer morphology and another possibility to reach an excellent PCE over 15%.
关键词： small-molecule acceptors,power conversion efficiencies,polymer solar cells
更新于2025-09-23 15:19:57
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Modifications of ZnO Interlayer to Improve the Power Conversion Efficiency of Organic Photovoltaic Cells
摘要： Power conversion efficiency (PCE) is an important parameter in determining the performance of organic photovoltaics (OPVs). Various factors lead to enhancement of power conversion efficiency. One such factor is doping of electron transport layer. A substantial increase in the power conversion efficiency of inverted organic solar cells is realized by a ZnO doped buffer layer acting as an electron-transport layer. Different works on Li, Cd, Ga, Al doping, introduction of C60 interface layer in ZnO buffer layer and dual doped system of InZnO-BisC60 have been reviewed here. The Al-doped buffer layer device showed the highest increase in power conversion efficiency.
关键词： Power conversion efficiency,Organic photovoltaics,ZnO interlayer,Doping
更新于2025-09-23 15:19:57
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Morphological control of TiO2 nanocrystals by solvothermal synthesis for dye-sensitized solar cell applications
摘要： TiO2 nanocrystals TETA1, TPRA2, TIPA3, TBUA4, TTBA5, and TBNA6 were prepared using ethanol, 1-propanol, isopropyl alcohol, n-butanol, tert-butyl alcohol, and benzyl alcohol, through the alcohol-based solvothermal method. The morphology, size, and crystallinity of the TiO2 nanocrystals were characterized utilizing transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and high-resolution transmission electron microscopy analyses. These six TiO2 nanocrystals with different morphologies were used as photoanodes in dye-sensitized solar cells (DSSCs) and their cell efficiencies were 8.08 % (TETA1), 8.38 % (TPRA2), 9.18 % (TIPA3), 7.68 % (TBUA4), 7.85 % (TTBA5), and 6.10 % (TBNA6). Among them, the well dispersed rod-shaped one-dimensional TiO2 (TIPA3) photoanode based cell showed the best power conversion efficiency due to its highest dye loading and excellent light-harvesting capacity. This TIPA3 cell demonstrated a fast electron transport rate with suppressed charge recombination which was confirmed from electrochemical impedance spectroscopy.
关键词： dye loading,TiO2 nanocrystals,power conversion efficiency,solvothermal synthesis,dye-sensitized solar cells
更新于2025-09-23 15:19:57
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Direct Observation of Crystal Engineering in Perovskite Solar Cells in a Moisture-Free Environment using Conductive Atomic Force Microscopy and Friction Force Microscopy
摘要： The origin of the increased efficiency of perovskite solar cells by control of environmental humidity was investigated using conductive atomic force microscopy (C-AFM) and friction force microscopy (FFM). The perovskite thin films fabricated in a humidity-free environment exhibited better crystallinity and lower number of trap sites than the films fabricated in a high-humidity environment. Through in-depth analysis using C-AFM and FFM, we found that there was locally decrystallized area in the perovskite structure fabricated in a high-humidity environment. By suppressing local decrystallization in a humidity-free environment, the power conversion efficiency (PCE) was increased by about 122%. This was mainly attributed to increase of the current density that elimination of the locally decrystallized area increase the effective active area. From this perspective, mapping local current and friction force using C-AFM and FFM could be new techniques for visualizing the effect of crystal engineering of perovskite solar cells in a humidity-free environment.
关键词： power conversion efficiency,crystallinity,perovskite solar cells,friction force microscopy,conductive atomic force microscopy,humidity
更新于2025-09-23 15:19:57
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Solutiona??Processed Polymer Solar Cells with over 17% Efficiency Enabled by an Iridium Complexation Approach
摘要： The commercially available PM6 as donor materials are used widely in highly efficient nonfullerene polymer solar cells (PSCs). In this work, different concentrations of iridium (Ir) complexes (0, 0.5, 1, 2.5, and 5 mol%) are incorporated carefully into the polymer conjugated backbone of PM6 (PM6-Ir0), and a set of π-conjugated polymer donors (named PM6-Ir0.5, PM6-Ir1, PM6-Ir2.5, and PM6-Ir5) are synthesized and characterized. It is demonstrated that the approach can rationally modify the molecular aggregations of polymer donors, effectively controlling the corresponding blend morphology and physical mechanisms, and finally improve the photovoltaic performance of the PM6-Irx-based PSCs. Among them, the best device based on PM6-Ir1:Y6 (1:1.2, w/w) exhibits outstanding power conversion efficiencies (PCEs) of 17.24% tested at Wuhan University and 17.32% tested at Institute of Chemistry, Chinese Academy of Sciences as well as a certified PCE of 16.70%, which are much higher than that of the control device based on the PM6-Ir0:Y6 blend (15.39%). This work affords an effective approach for further break through the reported champion PCE of the binary PSCs.
关键词： iridium complexation,morphology,polymer solar cells,power conversion efficiency
更新于2025-09-23 15:19:57
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Effect of insertion of bathocuproine buffer layer at grating-structured cathodea??organic-layer interface in bulk-heterojunction solar cells
摘要： A grating-structured interface of a poly(3-hexylthiophene) (P3HT) and n-type [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)-based bulk-heterojunction (BHJ) photovoltaic (PV) cell was designed and fabricated to obtain a desirable thickness distribution of the deposited bathocuproine (BCP) buffer layer to efficiently utilize its potentials. As a master mold of the grating-structure, a commercially available recordable digital versatile disc (DVD-R) substrate was employed. The grating-structured surface of the P3HT:PCBM layer was successfully produced by duplication from a poly(dimethylsiloxane) secondary mold using the spin cast molding technique. From morphological observations of the grating-structured surface covered with vapor-deposited BCP, we roughly estimated the ratio of the BCP thickness at “walls” to that at “top” and “bottom” regions to be ～0.5. The grating-type BHJ PV cell with a 5-nm-thick BCP layer exhibited the maximum power-conversion efficiency (ηp) of 3.51%. Compared with the conventional flat-type BHJ PV cell with a 20-nm-thick BCP layer, the performance of the grating-type BHJ PV cell with a 20-nm-thick BCP layer was remarkably improved, owing to the contribution of the wall side contact, which provides a lower-barrier path of the electrons toward the cathode through the thinner BCP layer.
关键词： bathocuproine buffer layer,grating-structured interface,bulk-heterojunction solar cells,power-conversion efficiency
更新于2025-09-23 15:19:57
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10.13% Efficiency Alla??Polymer Solar Cells Enabled by Improving the Optical Absorption of Polymer Acceptors
摘要： All-polymer solar cells (all-PSCs) are one of the most promising flexible and wearable energy generators due to their excellent morphology stability and mechanical robustness. However, it has been limited light absorption capacity for most polymer acceptors that hinders the improvement of power conversion efficiency (PCE) of all-PSCs. Herein, by simultaneously increasing the conjugation of the acceptor unit and enhancing the electron-donating ability of the donor unit, a novel narrow-bandgap polymer acceptor PF3-DTCO based on a A-D-A-structured acceptor unit ITIC16 and a carbon-oxygen (C-O)-bridged donor unit DTCO was developed. Extended conjugation of the acceptor units from IDIC16 to ITIC16 result in a red-shifted absorption spectrum and improved absorption coefficient without significant LUMO level reduction. Moreover, in addition to further broadening the absorption spectrum by the enhanced intramolecular charge transfer effect, the introduction of C-O-bridges into donor unit improves the absorption coefficient and electron-mobility, as well as optimizes the morphology and molecular order of active layers. As a result, the PF3-DTCO achieved a higher PCE of 10.13% with a higher short-circuit current density (Jsc) of 15.75 mA cm-2 in all-PSCs compared to its original polymer acceptor PF2-DTC (PCE=8.95% and Jsc=13.82 mA cm-2). Our work provides a promising method to construct high-performance polymer acceptors with excellent optical absorption for efficient all-PSCs.
关键词： optical absorption,all-polymer solar cells,polymer acceptor,carbon-oxygen-bridging,power conversion efficiency
更新于2025-09-23 15:19:57
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Effect of UV exposure of ITO/PEDOT:PSS substrates on the performance of inverted-type perovskite solar cells
摘要： We have fabricated inverted-type perovskite solar cells employing CH3NH3PbI3?xClx perovskite in the form of ITO/PEDOT:PSS/Perovskite/PCBM/Al. The effects of UV radiation on ITO/PEDOT:PSS substrates have been investigated for perovskite solar cells. ITO/PEDOT:PSS substrates were exposed to UV radiation for 5 to 15 min. The perovskite solar cells fabricated on UV-irradiated ITO/PEDOT:PSS substrates exhibited better performance as compared to those fabricated on substrates employing non-treated PEDOT:PSS. We used photovoltaic characterization, UV–VIS absorption, sheet resistance, X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and external quantum efficiency (EQE) characterization techniques to investigate the effect of UV irradiation of ITO/PEDOT:PSS substrates on the performance of perovskite solar cells. The devices fabricated on ITO/PEDOT:PSS (UV irradiated for 10 min) exhibited the best device performance of all. We achieved a 9% increase in the overall power conversion efficiency for the devices fabricated on substrates exposed to UV radiation.
关键词： Power conversion efficiency,ITO,Perovskite solar cells,PEDOT:PSS,UV irradiation
更新于2025-09-23 15:19:57
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Phenothiazine-Based Hole Transport Materials for Perovskite Solar Cells
摘要： The promising photovoltaic solar cells based on the perovskite light-harvesting materials have attracted researchers with their outstanding power conversion efficiencies (over 23% certified). The perovskite work has geared up in just under a decade and is competing with well-established semiconductor technologies such as silicon (Si), copper indium gallium selenide (CIGS), and cadmium telluride (CdTe). To commercialize the perovskite solar cells, their stability is the major concern. To address the stability issue, several factors need to be taken into account, and one of them is developing stable hole transport materials (HTMs), which are the essential building blocks. In this mini-review, we will discuss the important features of the HTMs, such as design and development of phenothiazine-based HTMs. Since phenothiazine is a low cost and stable molecule compared to the spiro-OMeTAD, it can be modified further via molecular engineering.
关键词： hole transport materials,phenothiazine,power conversion efficiencies,stability,perovskite solar cells
更新于2025-09-23 15:19:57