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Significantly enhanced electron transport of nonfullerene acceptor in blend film with high hole mobility polymer of high molecular weight: thick-film nonfullerene polymer solar cells showing high fill factor
摘要： Overcoming fill factor (FF) decay in thick fullerene active layers has been demonstrated with high hole mobility (μh) polymers. However, this issue remains as a challenge for thick active layers with nonfullerene acceptors. Here we demonstrate high FF and highly efficient nonfullerene based thick active layer with high μh polymer as the donor. Its relatively balanced hole and electron transports with a μh/μe ratio of 4.42 in 320 nm thick blend film are realized by the high molecular weight polymer induced higher electron mobility (μe approaching 1×10?3 cm2/(V s)) for the blend film. Relative to the pristine IEICO-4F nonfullerene film, 8 times increased μe for the blend film corresponds to closer interdigitation of IEICO-4F lamella and higher order face-on orientation of in-plain (200) peak of IEICO-4F molecules, which are very helpful for electron transport. As a result, solar cells with 320 nm thick binary nonfullerene active layers show outstanding FF over 70% and power conversion efficiency of 13.2%, a breakthrough for a high μh polymer as the donor. Our results suggest that high μh polymer donors are promising candidates for nonfullerene based polymer solar cells.
关键词： nonfullerene acceptor,thick-film polymer solar cells,fill factor,electron transport,high hole mobility polymer
更新于2025-09-23 15:21:01
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Influence of the Subcell Properties on the Fill Factor of Two-Terminal Perovskitea??Silicon Tandem Solar Cells
摘要： The performance of a tandem solar cell depends on the performance of its constituting subcells. Although this dependency is theoretically straightforward for open-circuit voltage (Voc) and short-circuit current, it is indirect for fill factor (FF) and thus for efficiency. We study here with simple simulations the effect on the tandem performance of each subcell FF by varying systematically their series resistance, parallel resistance, and local defect. We demonstrate that series resistance impacts strongly FF for single-junction devices but marginally for tandem devices, the opposite holding for parallel resistances (shunting). We show that localized defects will be most stringent to the tandem device when they occur in the current-limiting subcell. There is thus no obvious correlation between FFs of a tandem device and of its subcells. Finally, we compare two bottom-cell designs and highlight the importance of using a high-Voc bottom cell to reach high tandem efficiencies.
关键词： series resistance,tandem solar cells,parallel resistance,perovskite-silicon,local defects,fill factor
更新于2025-09-23 15:19:57
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Altering alkyl-chains branching positions for boosting the performance of small-molecule acceptors for highly efficient nonfullerene organic solar cells
摘要： The emergence of the latest generation of small-molecule acceptor (SMA) materials, with Y6 as a typical example, accounts for the surge in device performance for organic solar cells (OSCs). This study proposes two new acceptors named Y6-C2 and Y6-C3, from judicious alteration of alkyl-chains branching positions away from the Y6 backbone. Compared to the Y6, the Y6-C2 exhibits similar optical and electrochemical properties, but better molecular packing and enhanced crystallinity. In contrast, the Y6-C3 shows a significant blue-shift absorption in the solid state relative to the Y6 and Y6-C2. The as-cast PM6:Y6-C2-based OSC yields a higher power conversion efficiency (PCE) of 15.89% than those based on the Y6 (15.24%) and Y6-C3 (13.76%), representing the highest known value for as-cast nonfullerene OSCs. Prominently, the Y6-C2 displays a good compatibility with the PC71BM. Therefore, a ternary OSC device based on PM6:Y6-C2:PC71BM (1.0:1.0:0.2) was produced, and it exhibits an outstanding PCE of 17.06% and an impressive fill factor (FF) of 0.772. Our results improve understanding of the structure-property relationship for state-of-the-art SMAs and demonstrate that modulating the structure of SMAs via fine-tuning of alkyl-chains branching positions is an effective method to enhance their performance.
关键词： power conversion efficiency,fill factor,small molecular acceptor,alkyl-chain branching position,organic solar cell
更新于2025-09-23 15:19:57
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Increased efficiency of 23% for CIGS solar cell by using ITO as front contact
摘要： In this paper, a CIGS material based solar cell structure is proposed. The ef?ciency of the designed structure is improved by considering ITO (Indium Tin Oxide) as a front contact. The detailed analysis of the device is carried out thoroughly using SILVACO ATLAS. Various design parameters such as open-circuit voltage (Voc), the voltage at maximum power density, short circuit current density (Jsc), maximum output power (Pm), and ?ll factor (FF), are calculated. CIGS solar cell with ITO as a front contact gives an improved ef?ciency of 23.074%. Thus, the proposed solar cell is a suitable candidate for ultra-high ef?ciencies.
关键词： Fill factor,Ef?ciency,ITO,CIGS,Solar cell,TCAD
更新于2025-09-23 15:19:57
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Efficient NDT small molecule solar cell with high fill factor by pendant group engineering
摘要： Three naphthodithiophene (NDT)-based small molecules, bearing hexyl- (NDT-Hex), null (NDT) and fluorene (NDT-F) substituents at the β-position of the thiophene vertically conjugated to the NDT core, were designed and synthesized. The photovoltaic effect of engineered NDT molecules was investigated with detailed characterization on optical absorption, electronic energy levels, blend morphology, carrier mobility and photovoltaic performance conducted. It shows that the hexyl-substitution enhances the morphological tunability for NDT molecules, which contributes to achieve promising power conversion efficiency (PCE) with high fill factor (FF). The optimized solar cells based on NDT-Hex:PC71BM blends obtains a PCE of 6.7% with an FF of 0.717 and it reaches 8.6% with an FF of 0.638 if a non-fullerene molecular acceptor, NBDTP-Fout, was adopted to blend with NDT-Hex. Both FF are among the top ones of respective kind of solar cells based on NDT small molecule. The work demonstrates a feasible morphology-tuning method toward efficient organic solar cells with high FF.
关键词： morphology-tuning,naphthodithiophene,small molecule solar cells,high fill factor,pendant group engineering
更新于2025-09-23 15:19:57
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Investigation of electrical values of low-efficiency dye-sensitized solar cells (DSSCs)
摘要： Indium-tin-oxide (ITO)/density (d)- titanium dioxide (TiO2)/nonporous (nonp)-TiO2 is a TiO2-based bilayer photoanode. These photoanodes coated for dye-sensitized solar cells (DSSCs) were with nonp-TiO2 surface and had very thick ITO layer. DSSCs were fabricated with these photoanodes. After their current density-voltage (J-V) were analyzed, ?t was seen that they were low efficiency and the shape of their J-V curve was linear line instead of rectangle. In this study, it was examined the relationship between the dark current (IDC), the series resistance (Rs) and the shunt resistance (Rsh) were examined for evaluating the fill factor (FF) of low-efficiency DSSCs because of the photoanodes with nonp-TiO2 surfaces and very thick ITO for contact layer. It was seen in the J-V graph of DSSCs which had low FF value due to their IDC and low Rsh. The J-V graph of low-efficiency DSSCs is linear due to their low Rsh and high Rs values. Moreover, the too thick ITO layer decreases the resistance of photoanodes; however, electrons in these photoanodes can not efficiently transferred to external circuit from ITO contact layer of DSSCs.
关键词： Fill factor,Linear,Nonporous,Back electron,Low-efficiency,Dark current,Cell resistance
更新于2025-09-19 17:13:59
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Graphdiyne Derivative as Multifunctional Solid Additive in Binary Organic Solar Cells with 17.3% Efficiency and High Reproductivity
摘要： Morphology tuning of the blend film in organic solar cells (OSCs) is a key approach to improve device efficiencies. Among various strategies, solid additive is proposed as a simple and new way to enable morphology tuning. However, there exist few solid additives reported to meet such expectations. Herein, chlorine-functionalized graphdiyne (GCl) is successfully applied as a multifunctional solid additive to fine-tune the morphology and improve device efficiency as well as reproductivity for the first time. Compared with 15.6% efficiency for control devices, a record high efficiency of 17.3% with the certified one of 17.1% is obtained along with the simultaneous increase of short-circuit current (Jsc) and fill factor (FF), displaying the state-of-the-art binary organic solar cells at present. The redshift of the film absorption, enhanced crystallinity, prominent phase separation, improved mobility, and decreased charge recombination synergistically account for the increase of Jsc and FF after introducing GCl into the blend film. Moreover, the addition of GCl dramatically reduces batch-to-batch variations benefiting mass production owing to the nonvolatile property of GCl. All these results confirm the efficacy of GCl to enhance device performance, demonstrating a promising application of GCl as a multifunctional solid additive in the field of OSCs.
关键词： graphdiyne derivative,binary organic solar cells,high fill factor,high efficiency,solid additives
更新于2025-09-19 17:13:59
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Insight into the Efficiency and Stability of All-Polymer Solar Cells Based on Two 2D-Conjugated Polymer Donors: Achieving High Fill Factor of 78%
摘要： Achieving high fill factor (FF) is a great challenge for the all polymer solar cells (all-PSCs) since the FF can be influenced by numerous complicated factors. In this work, two medium bandgap 2D-conjugated copolymers J61 and J71 with varied side chains were utilized as donor to construct efficient all-PSCs with the typical electron-withdrawing polymer N2200 as acceptor. Eventually, moderate photovoltaic performance was obtained for J61:N2200 device with power conversion efficiency (PCE) of 6.58% and FF of 60.18%. While the J71:N2200-based all-PSCs delivered an outstanding PCE of 9.31% with an unprecedented FF of 78.00%. To the best of our knowledge, such an FF of 78% represents a record value for binary all-PSCs systems, which demonstrates that the all-PSCs can realize excellent FF comparable to other PSCs systems. The favorable blends morphology, molecular orientation, balanced charge transport and suppressed recombination together contributed to the remarkable photovoltaic performance of J71:N2200 devices. In addition, relatively weak thickness-dependence of photovoltaic property and excellent long-term device stabilities (in N2 and air, respectively) were observed for the J71:N2200 all-PSCs. These results reveal that J71 with trialkylsilyl side chains is a promising polymer donor candidate for developing high performance all-PSCs for future practical application.
关键词： high efficiency,fill factor,stability,all-polymer solar cells,donor
更新于2025-09-19 17:13:59
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Prickly pear fruit extract as photosensitizer for dye-sensitized solar cell
摘要： In this study, we have explored prickly pear fruit extract as a photosensitizer in dye-sensitized solar cells (DSSC). The photosensitizer was isolated from prickly pear fruits by extraction method using ethanol as solvent. Structural, morphological and optical properties of prickly pear extract characterized by XRD, SEM, UV-VIS-DRS, FTIR spectra, respectively. UV-VIS absorption and FTIR spectra of prickly pear fruit extract confirm the presence of betacyanin and hydroxyl groups anchoring onto the TiO2 surface. The absorption maxima at 534 nm in the visible region is prominent. The presence of betacyanin in the extract is indicative that the dye will be useful as a sensitizer in DSSC. Reflectance edge of TiO2 is red-shifted upon the adsorption of natural dye. The XPS analysis showed the charge state of hydroxyl (O-H) groups that are attached with the natural dye adsorbed onto the surface of TiO2. The fabricated DSSC had a conversion efficiency (?) of 0.56 % with highest fill factor (FF) of 85.0%, open-circuit voltage (Voc) of 0.56 V and short circuit-current density (Jsc) with 1.17 mA/cm2. The value obtained for the fill factor is promising to further explore the prickly pear extract for applicability in DSSC by improving the efficiency.
关键词： Dye-sensitized solar cells,Hydroxyl groups,Prickly pear fruit extract,Photosensitizer,TiO2,Fill factor,Betacyanin,Conversion efficiency
更新于2025-09-19 17:13:59
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Scanning a Silicon Photomultiplier with a Laser Beam
摘要： The Silicon Photomultiplier (SiPM) is a novel semiconducting photodetector which can detect single photons. It consists of many microcells (pixels) operating in the so-called Geiger mode. At present, there are two principal designs among such devices: surface pixel and deeply buried pixel (microwell) structures. The cellular structure decreases the device’s effective photosensitive area, expressed in terms of the geometrical fill factor. It is very important to take it into account when developing new constructions with high pixel densities that are necessary for increasing the dynamic range. It is believed that the fill factor of deep microwell SiPMs is close to unity. In this work, the technique and results of studying the zonal response of different SiPMs by scanning (moving) with micron laser spot are presented. It is shown that the geometrical fill factor of the deep microwell SiPM is less than 100% when detecting the red light (λ = 632 nm).
关键词： Silicon Photomultiplier,Geiger mode,geometrical fill factor,laser scanning,deep microwell SiPM,SiPM
更新于2025-09-16 10:30:52