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Tunnel oxide passivating electron contacts for high‐efficiency n‐type silicon solar cells with amorphous silicon passivating hole contacts
摘要： Organic photovoltaics (OPVs) consisting of a wide bandgap polymer donor and a nonfullerene acceptor (NFA) have received attention because they can effectively overcome the weaknesses of efficiency and stability for fullerene-based OPVs. One of the NFAs, ITIC, shows an excellent power conversion efficiency, as well as controllable solubility, absorption, crystallinity, and energy level. Thus, high-efficiency OPVs could be achieved by developing polymer donors appropriate for use with ITIC-based OPVs. In this study, the synthesized polymer donor, PBDTT-8ttTPD, containing alkylthieno[3,2-b]thiophene as π-bridge and thieno[3,4-c]pyrrole-4,6(5H)-dione (ttTPD) shows strong absorption with a sharp peak edge at around 700 nm. In addition, the high hole mobility and face-on oriented polymer structures in the blend films make ttTPD the best candidate for the donor in NFA-based OPVs. Notably, the molecular weight of the face-on preferred polymer donor is crucial for determining the power conversion efficiency (PCE) of the NFA-based devices. A high molecular weight improves the π?π stacking ordering, absorption, and nanomorphology of the blend films, resulting in a dramatic PCE improvement from 5.76% to 11.05% compared with that of the fullerene-based OPV device (7.86%).
关键词： organic photovoltaics,nonfullerene acceptors,molecular weight,TPD-based polymer,wide band gap donnor polymer
更新于2025-09-19 17:13:59
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A Nonfullerene Acceptor with Alkylthio‐ and Dimethoxy‐Thiophene‐Groups Yielding High‐Performance Ternary Organic Solar Cells
摘要： Herein, an A–D–A-type nonfullerene acceptor (named IDTS-4F) with an alkyl thiophenyl side chain and dimethoxy thiophene bridging unit is reported. The use of an alkyl thiophenyl group is important, as the insertion of sulfur atoms can slightly downshift the highest occupied molecular orbital (HOMO) level of the molecule and allows IDTS-4F to match with state-of-the-art donor polymer PM6 (or PM7). Compared with conventional nonfullerene acceptors, IT-4F, the IDTS-4F molecule, has a smaller optical bandgap and higher lowest unoccupied molecular orbital (LUMO) level, which are beneficial to increase the Voc and Jsc of the devices. Nonfullerene organic solar cell devices are fabricated using IDTS-4F. Although the binary device based on IDTS-4F exhibits a lower fill factor (FF, 70%), the ternary device by incorporating 0.2 of IDTS-4F and 0.8 of IT-4F (with PM6 as the donor polymer) can simultaneously achieve a higher Voc and Jsc, while maintaining the high FF (77%) of IT-4F based system. Morphology characterizations indicate the formation of homogeneous film morphology, the large increase in phase purity and crystallinity, and the reduction in domain size upon addition of crystalline IDTS-4F, while the electron/hole mobilities and recombination losses of the IT-4F system are both maintained.
关键词： polymer solar cells,nonfullerene acceptors,fullerene-free,organic solar cells,ternary solar cells
更新于2025-09-19 17:13:59
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Phenothiazine dyes containing a 4-phenyl-2-(thiophen-2-yl) thiazole bridge for dye-sensitized solar cells
摘要： Two novel phenothiazine dyes bearing a single or double cyanoacrylic acid acceptors, which share the same electron donor phenothiazine and the same 4-phenyl-2-(thiophen-2-yl)thiazole p-bridge, were synthesized. Thus, phenothiazine dyes with D-p-A and A-D-p-A framework were con?gured, and their photophysical properties and photovoltaic performance were investigated. The incorporation of another cyanoacrylic acid acceptor was found to bene?t the loading amount on TiO2, the light-harvesting ability, and the electron-injection ef?ciency. Dye with double cyanoacrylic acid acceptors showed a double short-circuit current compared with dye with a single acceptor. Therefore, dye with double cyanoacrylic acid acceptors achieved improved photoelectric conversion ef?ciency 4.35% (JSC ? 10.29 mA cm?2, VOC ? 0.65 V, FF ? 0.65) under standard global AM 1.5 G solar condition with dye N719 (7.19%) as a reference.
关键词： Phenothiazine,Photovoltaic performance,4-Phenyl-2-(thiophen-2-yl)thiazole,Double acceptors,Dye-sensitized solar cell
更新于2025-09-19 17:13:59
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A nona??fullerene acceptor with chlorinated thienyl conjugated side chains for higha??performance polymer solar cells via toluene processing
摘要： Small molecular acceptors (SMAs) BTC-2F and BTH-2F, based on heptacyclic benzodi(cyclopentadithiophene) electron-donating core (CBT) with chlorinated-thienyl conjugated and thienyl conjugated side chains, respectively, are designed and synthesized. Relative to non-chlorine acceptor BTH-2F, BTC-2F exhibits slightly blue-shifted absorption spectra, similar the lowest unoccupied molecular orbital (LUMO) (-3.91 eV), deeper highest occupied molecular orbital (HOMO) energy level and higher electron mobility than that of BTH-2F. PM6, a wide bandgap polymer, is selected as the donor material to construct bulk heterojunction polymer solar cells processed with nonhalogenated solvent toluene. The optimized PM6:BTC-2F-based device presents a 12.9% power conversion efficiency (PCE), while the PCE of PM6:BTH-2F-based device is only 11.3%. The results suggest that it is an effective strategy to optimize the photoelectric properties of SMAs by incorporating chlorine atom into the conjugated side chains.
关键词： small molecular acceptors,narrow bandgap,power conversion efficiency,chlorinated-thienyl,polymer solar cells
更新于2025-09-19 17:13:59
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Twoa??Dimension Conjugated Acceptors Based on Benzodi(cyclopentadithiophene) Core with Thiophenea??Fused Ending Group for Efficient Polymer Solar Cells
摘要： The previously reported nonfullerene small molecule ITIC-SF achieved via side chain tuning, promotes the power conversion efficiency of polymer solar cells (PSCs) with PBDB-T-SF as the donor from 10.1% and ITIC2 acceptors up to 12.2% for ITIC-SF acceptors. To further this research, benzene end groups of molecules are herein substituted with thiophene rings, obtaining two new molecules BDTCH-IC with alkylthio substituents, and BDTSF-IC with alkylthio and fluorine substituents on their thiophene-conjugated side chains. The absorption edges of BDTCH-IC and BDTSF-IC are red-shifted to 824 and 793 nm, respectively. Strengthened molecular crystallinity, promoted charge extraction, and upgraded morphology endorse the advancement of photovoltaic performance of the small molecular acceptors. Using donor PM6, the two small molecule acceptors show good photovoltaic performance, although the highest occupied molecular orbit energy offsets are small between donor and acceptor materials. As a combination of side-chain and end-group engineering, the photovoltaic performance of the PSCs is increased to 13.1%, together with the best short-circuit current (JSC) and fill factor reported thus far for this series of molecules. The results indicate that the modification of side chain and end groups is an effective way to improve the photovoltaic performance of small molecule acceptors.
关键词： small molecules acceptors,nonfullerenes,end groups,side-chain engineering,polymer solar cells
更新于2025-09-19 17:13:59
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Effects of Short‐Axis Alkoxy Substituents on Molecular Self‐Assembly and Photovoltaic Performance of Indacenodithiophene‐Based Acceptors
摘要： The effects of central alkoxy side chain length of a series of narrow bandgap small molecule acceptors (SMAs) on their physicochemical properties and on the photovoltaic performance of the SMA-based polymer solar cells (PSCs) are systematically investigated. It is found that the ordered aggregation of these SMAs in films is enhanced gradually with the increase of alkoxy chain length. The single-crystal structures of these SMAs further reveal that small changes in the side chain length can have a dramatic impact on molecular self-assembly. The short-circuit current density and power conversion efficiency values of the corresponding PSCs increase with the increase of the side chain length of the SMAs. The π–π coherence length of the SMAs in the active layers is increased with the increase of the side chain length, which could be the reason for the increase of the Jsc in the PSCs. The results indicate that small changes in side chain length can have a dramatic impact on the molecular self-assembly, morphology, and photovoltaic performance of the PSCs. The structure–performance relationship established in this study can provide important instructions for the side chain engineering and for the design of efficient SMAs materials.
关键词： polymer solar cells,side chain engineering,morphology,small molecule acceptors,molecular self-assembly
更新于2025-09-19 17:13:59
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PCE11-based polymer solar cells with high efficiency over 13% achieved by room-temperature processing
摘要： With the emergence and rapid development of new non-fullerene acceptors (NFAs), bulk-heterojunction polymer solar cells (BHJ-PSCs) have achieved high power conversion efficiencies (PCEs) over 16%. Developing effective methods to fabricate high-performance thick-film PSCs is important to meet the requirements of the future roll-to-roll commercial production. PffBT4T-2OD (PCE11) as the most promising temperature-dependent aggregation (TDA) donor with high crystallinity has achieved high performance at high film thickness, which, however, needs at high processing temperature and is detrimental for practical production of large-area PSCs. We designed NFAs, ZITI-N-CH3, ZITI-N-C8H17, and ZITI-N-EH containing different side chains. Because of the excellent miscibility of the TDA-polymer PffBT4T-2OD and ZITI-N-R, the devices can be fabricated at room temperature, achieving a medium PCE of 8.78% for ZITI-N-CH3-based PSC, a high PCE of 12.13% for ZITI-N-C8H17-based PSC and a superior PCE of 13.07% for ZITI-N-EH-based PSC, which is attributed to the smallest domain size and highest crystallization for PffBT4T-2OD:ZITI-N-EH blend. The PCE of 13.07% is the highest among the TDA polymer-based PSCs, which can be maintained at 12.35% at the high thickness of 200 nm. This work provides an important guideline to develop high-performance thick-film TDA-polymer-based non-fullerene PSCs at mild processing conditions.
关键词： temperature-dependent aggregation,room-temperature processing,polymer solar cells,high efficiency,non-fullerene acceptors
更新于2025-09-19 17:13:59
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17.1% Efficient Singlea??Junction Organic Solar Cells Enabled by na??Type Doping of the Bulka??Heterojunction
摘要： Molecular doping is often used in organic semiconductors to tune their (opto)electronic properties. Despite its versatility, however, its application in organic photovoltaics (OPVs) remains limited and restricted to p-type dopants. In an effort to control the charge transport within the bulk-heterojunction (BHJ) of OPVs, the n-type dopant benzyl viologen (BV) is incorporated in a BHJ composed of the donor polymer PM6 and the small-molecule acceptor IT-4F. The power conversion efficiency (PCE) of the cells is found to increase from 13.2% to 14.4% upon addition of 0.004 wt% BV. Analysis of the photoactive materials and devices reveals that BV acts simultaneously as n-type dopant and microstructure modifier for the BHJ. Under optimal BV concentrations, these synergistic effects result in balanced hole and electron mobilities, higher absorption coefficients and increased charge-carrier density within the BHJ, while significantly extending the cells’ shelf-lifetime. The n-type doping strategy is applied to five additional BHJ systems, for which similarly remarkable performance improvements are obtained. OPVs of particular interest are based on the ternary PM6:Y6:PC71BM:BV(0.004 wt%) blend for which a maximum PCE of 17.1%, is obtained. The effectiveness of the n-doping strategy highlights electron transport in NFA-based OPVs as being a key issue.
关键词： nonfullerene acceptors,molecular doping,additives,organic photovoltaics
更新于2025-09-19 17:13:59
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Optoelectronic properties and aggregation effects on the performance of planar versus contorted pyrene-cored perylenediimide dimers for organic solar cells
摘要： In this work, we present a new strategy to develop small molecules based on perylenediimde (PDI) with fused and contorted conjugated backbones as electron acceptors for fullerene-free organic solar cells. The two new electron acceptors, 27-Py-PDI and 49-Py-PDI, containing binary PDI units fused with pyrene at different positions were structurally isomers, which were investigated systematically. Theoretical calculations indicated that the two positional isomers exhibit distinct molecular geometries (planar for 27-Py-PDI vs contorted for 49-Py-PDI), which lead to huge differences on their synthetic methods, aggregation effects and their optoelectronic properties. The effects of structural isomerism on the molecular geometry, optical spectra, energy levels, charge carrier mobility and the morphology discrepancies as well as the corresponding photovoltaic performance were fully investigated. Temperature-dependent 1H NMR and the film UV-vis spectroscopy were used to study the molecular aggregation behaviors. Calculations of nuclear independent chemical shifts (NICS) indicate significant difference of the aromaticity between the isomers. Blended with donor materials of PTB7-Th to fabricate the inverted solar cells, an encouraging PCE of 4.53% along with an impressive open-circuit voltage (VOC) of 1.0 V (higher than the other acceptors based on PDIs and the PC71BM) were achieved by using 49-Py-PDI, which were superior to those of its isomer 27-Py-PDI (2.51%). The work suggests that introducing rigid and contorted features into fully fused acceptors based on PDI motifs can enhance the interface energy gap (?EDA), extend the π-delocalization and decrease the conformational disorder resulting into improved VOC without sacrificing JSC in OPV devices. This design strategy by introducing rigid and steric hindrance to increase intermolecular strain to construct fully ring fused contorted acceptors is an effective approach for the development of novel NFAs.
关键词： fused perylenediimides,pyrene core,non-fullerene acceptors,contorted conformation
更新于2025-09-19 17:13:59
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Fullerene's ring: A new strategy to improve the performance of fullerene organic solar cells
摘要： Fullerene is a common acceptor of organic solar cells (OSCs), therefore, it is of great significance to improve the performance of fullerene OSCs. Meanwhile, π-π stacking plays a crucial part in charge transfer and transport, so improving π-π stacking of fullerene OSCs is vital for achieving high efficiency in OSCs. In this work, we report a new strategy of adding [9]cycloparaphenylene ([9]CPP) as the third component in active layers, which affects the π-π stacking and improves the short-circuit current density (JSC) and fill factor (FF). As a result, a high power conversion efficiency (PCE) of 11.03% was obtained in PTB7-Th:[9]CPP:PC71BM ternary OSCs, which is nearly 20% higher than that of binary devices. At the same time, after [9]CPP is added PBDB-T:PC71BM and PTB7-Th:PCBM binary OSCs the PCE increases by 20% and 10% respectively. [9]CPP and fullerene acceptors formed [9]CPP?fullerenes system due to concave-convex π-π interactions, which was verified by density functional theory (DFT), and this system is first reported in OSCs. [9]CPP?fullerenes system affects the π-π stacking of acceptors, not only promotes charge transfer between donor and acceptor, but also enhances charge transport between the acceptor, thus improving the JSC. Furthermore, with the help of [9]CPP?fullerene system, the whole film is formed a nano-inter-transmission network, obtained a better appearance and improved FF. The results show that encapsulating fullerene of [9]CPP is indeed a resultful strategy for improving the performance of fullerene OSCs.
关键词： organic solar cells,cycloparaphenylenes,fullerene acceptors,ternary solar cell
更新于2025-09-19 17:13:59