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Functionalization of fullerene by polyethylene glycol toward promoted electron transport in inverted polymer solar cells
摘要： A novel polyethylene glycol-functionalized fullerene derivative (C60-PEGA) was synthesized by a facile one-step nucleophilic addition reaction. C60-PEGA possessed good solubility in methanol and was estimated as C60-( C8H18N)13H13O with average PEG moiety of 13 by 1H NMR, FT-IR and X-ray photoelectron spectroscopy (XPS) spectra. C60-PEGA was applied as an ETL to construct inverted bulk heterojunction polymer solar cells (inverted BHJ-PSCs) based on photoactive layers of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]: [6,6]-phenyl-C71-butyric acid methyl ester (PTB7-Th: PC71BM), which achieve the best PCE of 9.25%, surpassing that of reference device based on the ZnO ETL (8.61%). The higher ETL performance of C60-PEGA ETL in BHJ-iPSC device relative to that of the ZnO ETL was attributed to the increase of electron mobility and effective electron transport from the active layer to the ITO cathode because that the reduced work function (WF) of ITO via the modification of C60-PEGA leads to the increase of short-circuit current density (Jsc) and consequent PCE.
关键词： polyethylene glycol (PEG),electron transport layers (ETLs),inverted polymer solar cells,work function,fullerene derivative
更新于2025-09-19 17:13:59
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1 V high open-circuit voltage fluorinated alkoxybiphenyl side-chained benzodithiophene based photovoltaic polymers
摘要： Utilizing two-dimensional (2-D) conjugated structure and extending two-dimensional π-conjugation system with benzene can improve the performance of the BDT-based polymer solar cells (PSCs). In this work, combining with strong electron-drawing ability of fluorine atom, a new monomer BBFBDT with fluorinated alkoxybiphenyl unit as side-chain was designed and synthesized to construct medium band-gap donor (D) - acceptor (A) copolymer P1 with a benzo[1,2- c:4,5-c’]dithiophene-4,8-dione (BDD) acceptor. Blending with a classical non-fullerene acceptor ITIC, the P1-based PSCs reached a power conversion efficiency (PCE) of 4.16% and when coupled with a fullerene acceptor PC71BM, the PCE of PSCs reached 4.66% with an open-circuit voltage (Voc) of 0.93 V, a short-circuit current density (Jsc) of 9.83 mA cm?2 and a fill factor (FF) of 50.97%. The relatively poor Jsc of P1-based devices may be caused by the bad complementarity of absorption spectra. Furthermore, a wide band-gap D-A copolymer P2, with a electron-deficient 4,7-bis(5-bromothiophen-2-yl)-2-((2-ethylhexyl)oxy)-5,6-difluoro-2H-benzo[d][1,2,3]triazole (TZ) as the acceptor unit, was synthesized to match the absorption spectra of ITIC. Finally, the efficiency achieved 6.59% with Voc of 0.99 V, Jsc of 14.37 mA cm?2 and FF of 46.32%.
关键词： Fluorinated alkoxybiphenyl side-chain,Benzodithiophene (BDT),High open-circuit voltage,Conjugated polymers,Polymer solar cells
更新于2025-09-19 17:13:59
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Thieno[2,3-f]benzofuran based donor-acceptor polymer for fullerene-free solar cells
摘要： A donor–acceptor (D–A) polymer, PTBFDO-BDD, based on thieno[2,3-f]benzofuran (TBF) with 4-dodecyl thienyl chains, was designed and synthesized. The optical, electrochemical, photovoltaic and device active layer morphology properties of the new polymer were investigated. With the structure of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/PTBFDO-BDD:ITIC/PDINO/Al, polymer solar cells device exhibited a power conversion efficiency (PCE) of 7.15% (AM1.5G, 100 mW cm?2) with VOC of 0.803 V, JSC of 14.71 mA cm?2, and FF of 60.57%. This work demonstrates that thieno[2,3-f]benzofuran-based conjugated polymers are promising as polymer solar cells donor materials.
关键词： Non-fullerene acceptor,Polymer solar cells,Thieno[2,3-f]benzofuran
更新于2025-09-19 17:13:59
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π–π Stacking Distance and Phase Separation Controlled Efficiency in Stable All-Polymer Solar Cells
摘要： The morphology of the active layer plays a crucial role in determining device performance and stability for organic solar cells. All-polymer solar cells (All-PSCs), showing robust and stable morphologies, have been proven to give better thermal stability than their fullerene counterparts. However, outstanding thermal stability is not always the case for polymer blends, and the limiting factors responsible for the poor thermal stability in some All-PSCs, and how to obtain higher efficiency without losing stability, still remain unclear. By studying the morphology of poly [2,3-bis (3-octyloxyphenyl) quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl](TQ1)/poly[4,8-bis[5-(2-ethylhexyl)-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl]] (PCE10)/PNDI-T10 blend systems, we found that the rearranged molecular packing structure and phase separation were mainly responsible for the poor thermal stability in devices containing PCE10. The TQ1/PNDI-T10 devices exhibited an improved PCE with a decreased π–π stacking distance after thermal annealing; PCE10/PNDI-T10 devices showed a better pristine PCE, however, thermal annealing induced the increased π–π stacking distance and thus inferior hole conductivity, leading to a decreased PCE. Thus, a maximum PCE could be achieved in a TQ1/PCE10/PNDI-T10 (1/1/1) ternary system after thermal annealing resulting from their favorable molecular interaction and the trade-off of molecular packing structure variations between TQ1 and PCE10. This indicates that a route to efficient and thermal stable All-PSCs can be achieved in a ternary blend by using material with excellent pristine efficiency, combined with another material showing improved efficiency under thermal annealing.
关键词： morphology,device stability,crystallinity,all-polymer solar cells,thermal annealing,molecular packing structure
更新于2025-09-19 17:13:59
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Understanding the Morphology of High-performance Solar Cells Based on a Low Cost Polymer Donor
摘要： A low cost and high performance bulk heterojunction (BHJ) solar cell comprising an emerging polymer donor, poly[(thiophene)-alt-(6,7-difluoro-2-(2-hexyldecyloxy)quinoxaline)] (PTQ10), shows an efficiency of 12.7%. To improve performance of the solar cells, a better understanding of the structure-property relationships of the PTQ10-based devices is crucial. Here, we fabricate PTQ10/nonfullerene and fullerene BHJ devices, including PTQ10/IDIC, PTQ10/ITIC, and PTQ10/PC71BM, processed with or without thermal annealing and additive, provide detailed descriptions of the relationships between the morphology and performance. PTQ10 is found to be highly miscible with nonfullerene IDIC and ITIC acceptors, and poorly miscible with fullerene PC71BM acceptors. Thermal annealing promotes the crystallization of PTQ10 and phase separation of all PTQ10/IDIC, PTQ10/ITIC, and PTQ10/PC71BM devices, leading to an increased power conversion efficiencies (PCE) of the PTQ10/IDIC and PTQ10/ITIC devices but a decreased PCE of PTQ10/PC71BM devices with 1,8-di-iodooctane (DIO) additive. Without thermal annealing, DIO greatly improves the morphology of PTQ10/PC71BM, leading to a higher PCE. The results show that the degree of phase separation and ordering in the PTQ10-based devices significantly influence device performance. The morphology-property correlations demonstrated will assist in the rational design of this low cost polymer donor based solar cells to achieve even higher performance.
关键词： morphology,phase separation,polymer solar cells,miscibility,crystallization
更新于2025-09-19 17:13:59
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Synergistic Effects of Polymer Donor Backbone Fluorination and Nitrogenation Translate into Efficient Non-Fullerene Bulk-Heterojunction Polymer Solar Cells
摘要： State-of-the-art non-fullerene bulk-heterojunction (BHJ) polymer solar cells outperform the more extensively studied polymer–fullerene BHJ solar cells in terms of efficiency, thermal- and photo-stability. Considering the strong light absorption in near infrared region (600–1000 nm) for most of efficient acceptors, the exploration of high-performing large bandgap (LBG) polymer donors with complementary optical absorption ranging from 400 nm to 700 nm remains critical. In this work, the strategy of concurrently incorporating fluorine (–F) and unsaturated nitrogen (–N) substituents along the polymer backbones is used to develop LBG polymer donor PB[N][F]. Results show that the F– and N–substituted polymer donor PB[N][F] realizes up to 14.4% efficiency in BHJ photovoltaic devices when paired with a benchmark molecule acceptor Y6, which largely outperforms the analogues PB with efficiency of only 3.6% and PB[N] with efficiency of 11.8%. Systematic examinations show that synergistic effects of polymer backbone fluorination and nitrogenation can significantly increase ionization potential values, improve charge transport and reduce bimolecular recombination and trap-assisted recombination in PB[N][F]:Y6 BHJ system. Importantly, our study shows that the F– and N–substituted conjugated polymers are promising electron donor materials for solution-processed non-fullerene BHJ solar cells.
关键词： large-bandgap,fluorination,polymer solar cells,nitrogenation,bulk-heterojunction
更新于2025-09-19 17:13:59
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Two-Dimensional Bi <sub/>2</sub> O <sub/>2</sub> Se with High Mobility for High-Performance Polymer Solar Cells
摘要： Carrier mobility is a critical factor for power conversion efficiency (PCE) of polymer solar cells (PSCs), and the low charge carrier mobility still limits performance improvement of PSCs. Adding high mobility material into the active layer is one of the better ways to enhance the PCE of PSCs. Two-dimensional (2D) Bi2O2Se can be an ideal additive material for improving the carrier mobility of PSCs because its ultrahigh mobility and high thermal stability. In this work, the Bi2O2Se few-layer 2D nanoflakes are fabricated by combining lithium intercalation with shear force-assisted liquid phase exfoliation and applied as an additive to promote charge transport in PSCs for the first time. The 2D Bi2O2Se nanoflakes, when introduced into the active layer, not only provide new interface between donor and acceptor and efficient charge transfer pathways but also induce crystallization of photosensitive layer and form the continuous interpenetrating networks, which promotes the exciton separation and charge transfer in photosensitive layer. As a result, the PCE of device based on PBDB-T:ITIC is increased from 10.09% (0 wt%) to 12.22% (2 wt%). Meanwhile, the PCE of device based on PM6:Y6 is also increased from 14.59% for binary device to 16.28% for optimized ternary device (2 wt%). Moreover, the optimized ternary device shows excellent air stability by suppressing the mixing of the two phases. This work supplies a good method to enhance the PCE of PSCs, also shows the Bi2O2Se material has a good prospect in photovoltaic devices.
关键词： crystallinity,charge recombination,Polymer solar cells,stability,carrier mobility,2D Bi2O2Se flakes
更新于2025-09-19 17:13:59
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Optimizing the Phase-Separated Domain Size of the Active Layer via Sequential Crystallization in All-Polymer Solar Cells
摘要： Proper domain size of the active layer plays a key role in determining the exciton dissociation and charge transport in all polymer solar cells (all-PSCs). However, fine-tuning the domain size remains challenging due to low glass transition temperature and negligible mixing entropy in polymer blends. Herein, we systematically studied the influence of “crystallization kinetics” on the domain size and proposed that if donor and acceptor crystallize simultaneously, it is prone to form large domain size; while if sequential crystallization of donor and acceptor occurs, a fine phase separation structure with proper domain size can be obtained. Taking PBDB-T/PNDI blends for instance, the domain size was decreased by using sequential crystallization, meanwhile, the crystallinity and molecular orientation were optimized as well, boosting the power conversion efficiency (PCE) from 6.55% to 7.78%. This work provides a novel way to finely tune the heterojunction phase separation structures.
关键词： domain size,crystallization kinetics,sequential crystallization,all-polymer solar cells,phase separation
更新于2025-09-19 17:13:59
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The Role of Hydrogen-Bond Between Piperazine and Fullerene Molecules in Stabilizing Polymer:Fullerene Solar Cell Performance
摘要： Piperazine was recently reported as stabilizer for polymer:fullerene solar cells that can minimize the “burn-in” degradation of the cell. In this paper, the influence of N-substituents on the stabilization effect of piperazine in P3HT:PC61BM cells was investigated. Results confirmed that only piperazine derivatives (PZs) with N-H bond showed the stabilization effect, whereas the bis-alkyl substituted piperazine compounds do not able to improve the stability. Efficient photon-induced electron transfer (PET) process between PZ and PC61BM was only detected for the N-H containing PZ:PC61BM blends, corresponding ver well the stabilization effect of the PZs, which indicates that PET process of PZ and PC61BM stabilize the cell performance and the N-H bond plays a critical role ensuring the PET process and the consequent stabilization effect. Both 1H-NMR spectroscopy and theoretical calculation confirmed the formation of N-H…O-C and N-H…π bonds for the PC61BM-piperazine adduct, which was considered as the driving force that promotes the PET process between these two components. In addition, comparison of the calculated electron affinity energy (EA) and excitation energy (EEx) of PC61BM with/without piperazine confirmed that piperazine doping is able to promote the electron transfer (leads to the formation of PC61BM anions) than the energy transfer (leads to the formation of PC61BM excitons) between P3HT and PC61BM, which is beneficial for the performance and stability improvement.
关键词： Piperazine,Photochemistry,Degradation and Stability,Polymer Solar Cells,Hydrogen Bond
更新于2025-09-19 17:13:59
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An Ultravioleta??Deposited MoO <sub/>3</sub> Film as Anode Interlayer for Higha??Performance Polymer Solar Cells
摘要： An ultraviolet-deposited MoO3 film is developed as anode interlayer based on molybdenum(V) chloride as precursor. The ultraviolet-deposited MoO3 film is prepared from the precursor film (spin coated from its solution) with ultraviolet irradiation treatment, and the preparation process of the MoO3 film is facile, low cost, and compatible with mass production and flexible substrate. The composition of the MoO3 film is analyzed by X-ray photoelectron spectroscopy. The work function as well as the surface morphology and wettability of indium tin oxide (ITO) modified by the MoO3 film are investigated by ultraviolet photoelectron spectroscopy, atomic force microscopy, and contact angle tester, respectively, where the analyses show the ITO modified by the MoO3 anode interlayer can offer excellent energy level alignment and interface contact with active layer. The photovoltaic performance of nonfullerene polymer solar cells (PSCs) based on the MoO3 anode interlayer is researched with typical and relatively low-cost PBDB-T:ITIC as active layer, and the ITO/MoO3-based device shows the highest power conversion efficiency of 9.27% compared with the bare ITO-based device (3.69%) and the ITO/PEDOT:PSS-based device (9.15%). The results demonstrate the great potential of the ultraviolet-deposited MoO3 film as anode interlayer for high-performance PSCs.
关键词： ultraviolet irradiation,photovoltaic performance,MoO3 film,polymer solar cells,anode interlayer
更新于2025-09-19 17:13:59