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Iodine-assisted Antisolvent Engineering for Stable Perovskite Solar Cells with Efficiency >21.3 %
摘要： The quality of the photoactive film is a significant factor in determining the power conversion efficiency (PCE) and the stability of perovskite solar cells (PSCs). We report a simple upgraded antisolvent washing treatment using iodine modulation, which significantly improves the MAPbI3 films with high crystallinity and chemical uniformity. A detailed model for improving the mechanism is proposed to describe how the upgraded antisolvent enhances both the perovskite crystallization and passivates the under-coordinated Pb2+ dangling bond. PSCs fabricated with the FTO/TiO2/MAPbI3/Spiro-OMeTAD/Ag architecture used high quality films with less defective surfaces, present a PCE of 21.33 %, retaining 91 % of its initial value in ambient without any encapsulation after 30 days. These results provide insight into the surface defect passivation process achieved by halide ions balance while providing a simple and efficient process that can be extensively used to fabricate high-quality perovskite films.
关键词： power conversion efficiency,defect passivation,perovskite solar cells,antisolvent engineering,crystallization
更新于2025-09-19 17:13:59
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MV Power Conversion Systems Enabled by High-Voltage SiC Devices [Happenings]
摘要： The current electrical distribution system needs to adapt due to an increase in demand and requirements for a “smarter grid,” which are required because of the proliferation of distributed energy resources (DERs). Transformers form an integral part of these electrical grids, and an upgrade to handle the additional requirements that come along is imperative. Unfortunately, an upgrade in a conventional sense is not possible, so it is time to think beyond conventional transformers. Thanks to recent strides in power electronics research and the availability of high-voltage (HV) silicon carbide (SiC) power semiconductor devices, we can contemplate building a smart “solid-state transformer” to handle the demands of the smart grid. In electrical distribution systems, the transformers convert thousands of volts [medium voltage (MV)] into lower voltages that can be safely used in homes and businesses [1]. With emerging technologies in building and fabricating MV SiC-based power semiconductor devices, MV power conversion on a large-scale scenario seems feasible. While companies, such as Wolfspeed (CREE), General Electric, Infineon Technologies, Mitsubishi, and ROHM, continue to develop and improve these MV semiconductor devices, we at the FREEDM Systems Center are aiming at the application side of things to ensure a market for these power devices.
关键词： SiC devices,smart grid,solid-state transformer,MV power conversion,power conversion
更新于2025-09-16 10:30:52
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Role of long persistence phosphors on their enhancement in performances of photoelectric devices: in case of dye-sensitized solar cells
摘要： To enhancing enhanced sunlight harvesting, long persistence phosphor (LPP) materials were often incorporated into photoanodes of photoelectric devices. However, the role of LPP layer on the photoelectric enhancements is not yet clear. Here, the authors have systematically studied the effect of green LPP (SrAl2O4: Eu3+) and its thickness on photoelectric behaviours of dye-sensitized solar cells (DSSCs). Results showed that the P25/LPP DSSCs generates power conversion efficiency (PCE) of 7.16 % at the optimal LPP thickness, which is 24.3% higher than that of the P25 ones. Series of analysis indicate that the enhancements in short-circuit current density and PCE could mainly be due to the LPP’s function of back scattering (containing down-conversion effect and enhancement in light absorption) of incident sunlight. Moreover, the enhanced carriers’ lifetime and open-circuit voltage are mainly due to the LPP layer’s afterglow effect. In addition, the P25/LPP DSSCs can still generate an output power density (82.15 μW cm-2) with a high PCE value of 46.94% in dark.
关键词： Back scattering,Power conversion efficiency,Down conversion,Long persistence phosphors,Titanium dioxide (P25),Dye-sensitized solar cells
更新于2025-09-16 10:30:52
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Non‐Fullerene Organic Solar Cells Based on Benzo[1,2‐b:4,5‐b′]difuran‐Conjugated Polymer with 14% Efficiency
摘要： The development of high-performance donor polymers is important for obtaining high power conversion efficiencies (PCEs) of non-fullerene polymer solar cells (PSCs). Currently, most high-efficiency PSCs are fabricated with benzo[1,2-b:4,5-b′]dithiophene (BDT)-based conjugated polymers. The photovoltaic performance of benzo[1,2-b:4,5-b′]difuran (BDF)-based copolymers has lagged far behind that of BDT-based counterparts. In this study, a novel BDF-based copolymer L2 is designed and synthesized, in which BDF and benzotriazole (BTz) building blocks have been used as the electron-sufficient and deficient units, respectively. When blending with a non-fullerene small molecule acceptor (SMA), TTPT-T-4F, the L2-based device exhibits a remarkably high PCE of 14.0%, which is higher than that of the device fabricated by its analogue BDT copolymer (12.72%). Moreover, PSCs based on the L2:TTPT-T-4F blend demonstrate excellent ambient stability with 92% of its original PCE remaining after storage in air for 1800 h. Thus, BDF is a promising electron-donating unit, and the BDF-based copolymers can be competitive or even surpass the performance of BDT-based counterparts.
关键词： ambient stability,copolymer,organic solar cells,power conversion efficiency,benzo[1,2-b:4,5-b′]difuran
更新于2025-09-16 10:30:52
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[IEEE 2019 6th International Conference on Space Science and Communication (IconSpace) - Johor Bahru, Malaysia (2019.7.28-2019.7.30)] 2019 6th International Conference on Space Science and Communication (IconSpace) - Integration of NiO Layer as Hole Transport Material in Perovskite Solar Cells
摘要： A successful integration of inorganic hole transporting material (HTM) for perovskite become one of the major concerns due to the instability issue with organic HTM. Inorganic NiO films as an efficient HTM for the inverted perovskite solar cell has been deposited by electron beam vapor deposition (EBPVD) technique instated of solution process. The X-Ray diffraction (XRD) peak of as-deposited substrate corresponding to (1 1 1) and (2 0 0) plane are dominating. The non-stoichiometry (1 1 1) in NiO thin film formation at influence its charge transfer characteristics. The FESEM confirms the successful non-stoichiometric deposition of NiO on FTO glass in an elemental wt% of O2 (15.82) and Ni (23.62). The perovskite structure of solar cells are fabricated Glass/TCO/NiO/Perovskite/PCBM/BCP/Ag. The deposited perovskite solar cells show higher power conversion efficiency (PCE) 10.80% with short circuit current density (Jsc) of 15.13 (mA cm-2), open circuit voltage (Voc) of 0.967 (V), field factor (FF) of 73.83 (%) which also allows thinking of an alternative HTL other than organic HTL for realistic commercial purpose.
关键词： Perovskite solar cell,hole transporting materials,nickel oxide,vapor deposition technique,power conversion efficiency
更新于2025-09-16 10:30:52
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Modulation doping of absorbent cotton derived carbon dots for quantum dot-sensitized solar cells
摘要： In order to improve the power conversion efficiency (PCE) of quantum dot-sensitized solar cells (QDSC), a series of absorbent cotton derived carbon quantum dots (CQDs) with different dopants (namely carbamide, thiourea, and 1,3-diaminopropane) have been successfully synthesized by a one-pot hydrothermal method. The average particle sizes of the three doped CQDs are 1.7 nm, 5.6 nm, and 1.4 nm respectively, smaller than that of the undoped ones (24.2 nm). The morphological and structural characteristics of the four CQDs have been studied in detail. In addition, the three doped CQDs exhibit better optical properties compared with the undoped ones in the UV-vis and PL spectra. Then CQD-based QDSC are experimentally fabricated, showing that the short current density (Jsc) and open circuit voltage (Voc) of the QDSC are distinctly improved owing to the dopants. Especially the QDSC with the 1,3-diaminopropane doped CQD achieves the highest PCE (0.527%), 299% larger than that without dopant (0.176%). In order to highlight a reasonable mechanism, the UV-vis diffuse reflectance spectrum of CQD sensitized TiO2 and the calculated energy band structures of various CQDs are investigated. It’s found from the above analysis that the addition of carbamide, thiourea, and 1,3-diaminopropane is beneficial to obtain CQDs of smaller size, and with a smaller band gap and more nitrogenous or sulphureous functional groups, which enhance the light absorption performance and photo-excitation properties. The above factors are helpful to improve the Jsc of QDSC. Nitrogen, acting as a donor to the CQDs, will assist the sensitized photoanode with a higher Fermi level, resulting in a larger Voc of the QSDC. Finally this study builds the relation among the microstructure of the CQDs, three characteristics of the CQDs (namely the spectra, energy band structure and functional groups) and the photoelectric properties of the QDSC, which will provide guidance for the modulation doping of CQDs to improve the PCE of QDSC.
关键词： dopants,carbon quantum dots,hydrothermal method,power conversion efficiency,quantum dot-sensitized solar cells
更新于2025-09-16 10:30:52
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“Twisted” conjugated molecules as donor materials for efficient all-small-molecule organic solar cells processed with tetrahydrofuran
摘要： High-performance organic semiconductors that can be processed with environmentally benign solvents are highly desirable for printable optoelectronics. Herein, four acceptor–donor–acceptor conjugated molecules, i.e., DRTT-T, DRTT-R, DRTT-OR and DRTT, with 3-ethylrhodanine as acceptor terminal units and 2,5-bis(4,8-di(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b0]dithiophen-2-yl)thieno[3,2-b]thiophene derivatives as donor units were synthesized. 5-(2-Ethylhexyl)thiophen-2-yl, 2-ethylhexyl and 2-ethylhexyloxy were introduced at the b-positions of the central thieno[3,2-b]thiophene (TT) units in DRTT-T, DRTT-R and DRTT-OR, respectively, and unsubstituted TT was used as the central unit in DRTT. As revealed by density functional theory calculations, DRTT-OR and DRTT adopt an almost planar geometry, while DRTT-T and DRTT-R have “twisted” backbones due to the introduction of bulky substituents on TT units. Di?ering from DRTT-OR and DRTT which are only well soluble in chlorinated solvents such as chloroform, DRTT-T and DRTT-R also show high solubility in “greener” solvents, including toluene and tetrahydrofuran (THF). Non-fullerene small molecule (NFSM) organic solar cells (OSCs) were fabricated with these molecules as donor materials. The molecules (DRTT-T and DRTT-R) with twisted backbones displayed remarkably higher device performance compared to more planar ones (DRTT-OR and DRTT), attributed to the formation of ordered face-on microstructures with p–p stacking distances of 3.7–3.8 ?A and interpenetration networks of donor and acceptor components in the blend ?lms based on DRTT-T and DRTT-R. Most importantly, the power conversion e?ciencies (PCEs) of DRTT-T and DRTT-R based devices processed with THF reached 9.37% and 10.45%, respectively. This study demonstrates that “twisting” conjugated backbones is an appropriate strategy to design eco-friendly solvent processable organic semiconductors for high-e?ciency OSCs.
关键词： conjugated molecules,tetrahydrofuran,organic solar cells,donor materials,power conversion efficiencies
更新于2025-09-16 10:30:52
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High-efficiency non-halogenated solvent processable polymer/PCBM solar cells <i>via</i> fluorination-enabled optimized nanoscale morphology
摘要： PNTz4T-based polymers have been extensively employed in high-efficiency fullerene-based polymer solar cells (PSCs) with a power conversion efficiency (PCE) of approximately 10.0% due to the high crystallinity of these polymers. The introduction of two fluorine atoms into PNTz4T to synthesize the PNTz4T-2F polymer has boosted the PCE to 10.6%, but the introduction of four fluorine atoms to synthesize the PNTz4T-4F polymer negatively affects the efficiency (PCE ? 6.5%), implying that the number of fluorine atoms is not yet optimized. We have developed a new synthetic route for a novel monofluoro-bithiophene monomer and successfully synthesized a novel PNTz4T-1F polymer. The fullerene-based PSCs based on our novel PNTz4T-1F polymer processed using a halogen-free solvent system demonstrated an outstanding PCE of 11.77% (11.67% certified), representing the highest PCE reported thus far in the literature. Due to the optimum molecular ordering/packing, improved interaction with PC71BM and interconnectivity between photoactive material domains, PNTz4T-1F-based PSCs exhibit lower charge carrier recombination and enhanced charge carrier mobility levels, leading to a substantially high photocurrent density (20.37 mA cm(cid:2)2). These results create new means to tune the structural properties of polymers, ultimately leading to the realization of this class of solar cells for practical applications.
关键词： polymer solar cells,nanoscale morphology,halogen-free solvent,power conversion efficiency,fluorination
更新于2025-09-16 10:30:52
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Enhanced performance of ternary organic solar cells with a wide bandgap acceptor as the third component
摘要： Two n-type organic semiconductor (n-OS) acceptors, C8-SF and Y-MODF, were designed and synthesized for application in organic solar cells (OSCs). C8-SF shows a lower lowest unoccupied molecular orbital (LUMO) energy level and lower bandgap with an absorption edge at 822 nm. Y-MODF possesses a relatively larger bandgap and higher LUMO and lower HOMO (highest occupied molecular orbital) energy levels than C8-SF. With the polymer PM6 as the donor, the OSC with C8-SF as the acceptor delivers a power conversion efficiency (PCE) of 11.59% with a lower open circuit voltage (Voc) of 0.787 V, while the device with Y-MODF as the acceptor exhibits a lower PCE of 8.63% but a higher Voc of 0.984 V benefiting from the higher LUMO of the Y-MODF acceptor. Then, a series of ternary OSCs were fabricated with PM6:C8-SF as the host system and Y-MODF as a third component. The optimal ternary OSCs with 25% Y-MODF incorporated into the acceptor achieve a higher PCE of 13.39%, with an improved Voc of 0.845 V, a Jsc of 20.88 mA cm?2 and a FF of 75.87%. It was found that adding Y-MODF to the PM6:C8-SF binary system suppressed monomolecular recombination and improved the utilization of 450–600 nm range photons. Molecular packing is further optimized with more balanced hole and electron transport, thus resulting in the enhanced Jsc and FF for the ternary OSCs. These results indicate that the addition of a wide bandgap acceptor with a higher LUMO energy level to a binary donor/acceptor system may have potential for Voc and PCE improvement of ternary OSCs.
关键词： ternary OSCs,n-type organic semiconductor,organic solar cells,open circuit voltage,power conversion efficiency
更新于2025-09-16 10:30:52
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A universal approach for optimizing charge extraction in electron transporting layer-free organic solar cells <i>via</i> Lewis base doping
摘要： Although the improvement of power conversion efficiency (PCE) in organic photovoltaic cells (OSC) is due to the development of novel donors and non-fullerene acceptors, state-of-the-art devices commonly utilize charge transporting/extraction interlayers. Here we demonstrate a universal approach based on a series of tetraalkyl ammonium bromide (TXABr) Lewis bases as n-dopants for mediating electron extracting properties in a range of OSCs with non-fullerene or PCBM acceptors. Under optimal conditions, the TXABr-doped devices without electron transporting layers (ETLs) exhibit PCEs comparable to those of the ones based on a conventional device structure containing ETLs. We found that the doping efficiency of acceptors is intimately correlated with the chain length (Lchain) of dopants. In OSCs based on acceptors of ITIC derivatives (IT-4F, ITIC, ITM, and ITCC), similar Lchain-dependent doping efficiency and PCE modification are found, while for OSCs with acceptors bearing different structures in conjugated backbones or side chains, the selection rule of dopants to achieve the best performance enhancement is different. These correlations are explained by the mutual effects of electrostatic interaction in the dopants and steric hindrance between the dopants and acceptors, the latter of which is affected by the compatibility of side chains in the host and dopant. With TXABr doping, (quasi-)ohmic contacts for electrons are realized in these ETL-free devices, leading to expediting the charge sweepout with mitigated interfacial charge recombination. This work offers a promising pathway to realize high efficiency non-fullerene OSCs with simplified device architecture.
关键词： organic solar cells,power conversion efficiency,charge extraction,Lewis base doping,electron transporting layer-free
更新于2025-09-16 10:30:52