- 标题
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- 实验方案
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Probe and Control of the Tiny Amounts of Dopants in BHJ Film Enable Higher-Performance Polymer Solar Cells
摘要： In order to achieve efficient doping in polymer solar cell (PSC), the dopant needs to be selectively located in the binary components of bulk heterojunction (BHJ) film according to its polarity. The rarely studied n-type dopant is thoroughly examined in a simplified planar heterojunction (PHJ) device to address its favored location in the active layer. Results show that the n-dopant distributing in the acceptor layer or at the donor/acceptor interface produces enhanced device performance, whereas it harms the device when locating in the donor layer. Based on the results, the benefit of n-type doping is then transferred to the high-efficient BHJ devices via a sequential coating procedure. The performance improvement is closely linked with the variation of dopant’s location in the BHJ film, which is carefully examined by the synchrotron techniques with delicate chemical sensitivity. More interestingly, the sequential coating procedure can be easily extended to the p-doped device only by changing the dopant’s polarity in the middle layer. These findings pave the way of ambipolar doping in PSCs and make performance improvement by molecular doping within expectation.
关键词： molecular doping,Polymer solar cell,doped morphology,n-type doping,ternary blend solar cell
更新于2025-09-23 15:21:01
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Rational design of a novel isoindigo-based conjugated terpolymer with panchromatic absorption and its application to polymer solar cells
摘要： In this study, a panchromatic absorptive conjugated terpolymer, BDTID-BDT3MT, is synthesized, which consists of electron-donating benzodithiophene (BDT), isoindigo (ID) as a strong electron-accepting unit, and methyl-3-thiophenecarboxylate (3 MT) as a weak electron-accepting unit. By combining these three monomers into the structure of a conjugated terpolymer, the absorption spectrum of BDTID-BDT3MT is induced to exhibit an unusually broad, strong, and uniform band in the wavelength interval from 300 to 750 nm, which helps achieving highly efficient light harvesting under solar illumination. The intriguing panchromatic absorption behavior of BDTID-BDT3MT was explained on the basis of theoretical calculations using simplified repeating units. Polymer solar cells (PSCs) based on BDTID-BDT3MT as a donating polymer and non-fullerene acceptors (e.g., ITIC-4F) exhibited a high power conversion efficiency (PCE) of 5.38%, high open circuit voltage (Voc) of 0.88 V, and short circuit current density (Jsc) of 13.74 mA/cm2, while PSCs based on ternary blend systems consisting of BDTID, BDT3MT, and ITIC-4F exhibited lower PCE and Jsc of 3.74% and 11.15 mA/cm2, respectively. The superior performance of PSCs based on BDTID-BDT3MT can be attributed to their high light harvesting efficiencies and relatively more favorable nano-phase film morphologies. Our results establish that BDT, ID, and 3 MT units serve as useful building blocks in the structure of conjugated terpolymers due to their remarkably broad panchromatic absorption band.
关键词： Panchromatic absorption,Terpolymer,Benzodithiophene,Isoindigo,Polymer solar cell
更新于2025-09-23 15:21:01
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The influence of UV filter and Al/Ag moisture barrier layer on the outdoor stability of polymer solar cells
摘要： The degradation of the polymer solar cells in the outdoor condition was studied. It was found that the devices with normal structure (ITO/PEDOT:PSS/PBDTTT-EFT:PC71BM/ZrOx/Al) show better stability than those with inverted device structure (ITO/ZnO/PBDTTT-EFT:PC71BM/MoO3/Ag). PBDTTT-EFT is poly[4, 8-bis(5-(2-ethylhexyl) thiophen-2-yl) benzo [1,2-b;4,5-b'] dithiophene-2, 6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno [3,4-b] thiophene-) ?2-carboxylate-2-6-diyl)] and PC71BM is [6,6]-phenyl-C71-butyric acid methyl ester. The major cause of degradation was attributed to the ultraviolet (UV) part of the sunlight. When the UV filter with cut-off wavelength of 400 nm was used to protect the device, the decay rate was improved by 50 times and the protected device retains 95% of their initial power conversion efficiency after 13 days outside. In the meanwhile, the decay of device fabricated by toluene was found 8 times faster than device by chlorobenzene. Thin 20 nm of Ag capping layer can further improve the stability. Degradation under water immersion indicates that the major effect of Ag is to protect against the residual moisture inside the encapsulation.
关键词： Polymer solar cell,Solution-processable,Ultraviolet stability,Moisture barrier
更新于2025-09-23 15:19:57
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Significance of Dopant/Component Miscibility to Efficient N-Doping in Polymer Solar Cells
摘要： The uncertain dopant location in the bulk heterojunction (BHJ) film hinders the wide application of molecular doping in polymer solar cells (PSCs) as is in other organic devices. It is known that the interaction between dopant and component governs the dopant distribution in the BHJ film, and thus largely controls the effectiveness of molecular doping. After excluding the strong dopant/component interaction by forming the charge-transfer complex in solution, we estimate the dopant/component miscibility by calculating the difference of Hansen’s total solubility parameters (δi-Hansen) and prove its correctness by contact angle measurements, and two model systems of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophe-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl -5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione))] (PBDB)/poly{[N,N’-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5’-(2,2’-bithiophene)} (N2200) and poly[4,8-bis(5-(2-ethylhexyl)-thiophene-2-yl)benzo[1,2-b;4,5-b’]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl]] (PCE10)/N2200 are selected to reveal the miscibility-photovoltaic performance relations. Only the material combination with large δi-Hansen between n-dopant (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl) phenyl) dimethylamine (N-DMBI) and the donor polymer achieves enhanced photovoltaic performance. After that, we examine the doped morphology of polymer blends. Since the polymers’ crystallizations are negatively affected by N-DMBI addition, we ensure the significance of n-doping on the enhanced device performance. Besides the dopant/polymer interaction, the solvent/polymer and solvent/dopant interactions are also considered to evaluate the kinetic effect on N-DMBI distribution by drawing the ternary phase diagram. We conclude that the kinetic morphological evolution doesn’t change the miscibility governed N-DMBI distribution in the BHJ film. Finally, we provide a direct relationship between the N-DMBI position and the device property by fabricating the bi-layer devices. The enhancement of photovoltaic performances is observed in both of material systems only if the N-DMBI distributes in N2200. Our work outlines a basis for using the dopant/component interaction and ternary phase diagram to predict the dopant distribution before extensive experiments. It significantly reduces the trial-to-error work and increases the reliability of molecularly doped PSCs.
关键词： n-doping,polymer solar cell,doped morphology,ternary phase diagram,Molecular doping
更新于2025-09-23 15:19:57
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Efficient Low-Cost All-Flexible Microcavity Semitransparent Polymer Solar Cells Enabled by Polymer Flexible One-Dimensional Photonic Crystals
摘要： High-efficiency low-cost all-flexible microcavity semitransparent polymer solar cells (STPSCs) are comparatively studied in both fullerene- and nonfullerene-based systems with the structure strategy employing polymer flexible one-dimensional photonic crystals (F-1DPCs), as well as ITO-free UV/ozone plasma-treated polymer/ultrathin metal and PEDOT:PSS transparent electrodes. Based on the reasonable optimization of electrical and optical characteristics in device, the maximum power conversion efficiency with the use of polymer F-1DPCs can be greatly improved by 24~27% compared to the respective control devices. The improvement in JSC is comprehensively discussed, which is mainly ascribed to the enhancement of effective photon absorption in device. Although color tunability of fullerene and nonfullerene all-flexible STPSCs can be easily achieved with the use of different photonic bandgaps of polymer F-1DPCs, the CIE coordinates of nonfullerene STPSCs differ a lot from the original light source compared to the fullerene ones due to a high absorption coefficient in a narrow wavelength region. This work presents an easy and effective microcavity device strategy incorporated with different elements and demonstrates a new sketch of structure-absorption-performance relationships for fullerene- versus nonfullerene-based all-flexible STPSCs, which is compatible with low-cost roll-to-roll manufacturing and surely has a diversity of potential applications to better meet specific needs.
关键词： all-flexible,polymer solar cell,semitransparent,polymer flexible one-dimensional photonic crystals,microcavity
更新于2025-09-19 17:13:59
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Mechanistic insights into the effect of polymer regioregularity on thermal stability of polymer solar cells
摘要： Thermal stability is a bottleneck toward commercialization of polymer solar cells (PSCs). The effect of PCBM aggregation in multi-length-scale on the bulk-heterojunction (BHJ) structure, performance, and thermal stability of PSCs is studied here by grazing-incidence small- and wide-angle X-ray scattering. The evolution of hierarchical BHJ structures of the blend film tuned by regioregularity of polymers from the as-cast state to the thermally unstable state was systematically investigated. The thermal stability of PSCs with high polymer regioregularity value can be improved because of the good mutual interaction between polymer crystallites and fullerene aggregation. The insights obtained from this study provide an approach to manipulate the film structure in a multi-length scale and to enhance the thermal stability of P3HT-based PSCs.
关键词： PCBM aggregation,bulk heterojunction,nanostructure,polymer solar cell,GIXRD,thermal stability
更新于2025-09-19 17:13:59
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Synthesis of a new wide-bandgap conjugated copolymer with 3-trifluoromethylthiophene monomer and Its application to non-fullerene polymer solar cells
摘要： In this study, a novel wide-bandgap conjugate donor-acceptor type copolymer, PBDT-TFMTh, containing benzodithiophene (BDT) as a donor unit and trifluoromethyl (TFM)-substituted thiophene (Th) as an acceptor unit was designed and synthesized. The physical, optical, and electrochemical properties of PBDT-TFMTh were studied in detail and it was found to have lower-lying highest occupied and lowest unoccupied molecular orbitals. The polymer solar cell with an active layer consisting of PBDT-TFMTh and acceptor IDT(TCV)2 showed a relatively high power conversion efficiency of 2.25% after thermal annealing at 120 (cid:1)C.
关键词： power conversion efficiency,wide-bandgap copolymer,3-trifluoromethylthiophene,polymer solar cell
更新于2025-09-19 17:13:59
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Efficient Charge Transfer and Carrier Extraction in All-Polymer Solar Cells Using an Acceptor Filler
摘要： All-polymer solar cells (all-PSCs) exhibit considerably improved mechanical and thermal stability than their polymer-fullerene counterparts. Despite their advantages, the power conversion efficiencies of all-PSCs are still lower than those of polymer-fullerene PSCs. In this study, we demonstrate that introducing a small amount of fullerene or nonfullerene acceptors as filler into the photoactive layer of PBDBT:N2200 all-PSCs can enhance charge transport properties, thereby the device performance. An appreciable enhancement (~21%) in the power-conversion-efficiencies (PCEs) of all-PSCs, from 6.13% to 7.42%, is obtained when fullerene with the amount of 25 wt% PBDBT is added. The performance improvement is primary from the enhanced short circuit current density (Jsc), which can be attributed to the enhanced exciton dissociation, reduced charge recombination, and balanced charge transport in the prescence of the fullerene filler. Similar behavior is also observed when fullerene is replaced by ITIC molecules. Importantly, the fullerene filler shows a negiligible effect on the device storage and light-soaking stability. Therefore, all-PSCs incorporating a proper selected acceptor filler is an efficient way to improve device performance without sacrificing stability. We believe that our study can pave a useful approach for developing stable and high performance PSCs.
关键词： filler,all-polymer solar cell,charge transport,ternary,charge extraction
更新于2025-09-19 17:13:59
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Thermal-Annealing Effects on Energy Level Alignment at Organic Heterojunctions and Corresponding Voltage Losses in All-Polymer Solar Cells
摘要： Matched energy level alignment is a key requirement for efficient organic devices such as organic light-emitting diodes, photovoltaics, and field-effect transistors. The effect of thermal stress/annealing on energy level alignment and related properties of the devices are less discussed compared to the extensively explored effect on morphology and corresponding device performance. Here all polymer solar cells (all-PSCs) are employed to study thermal annealing effects on energy level alignment and the corresponding effect on the device properties of the all-PSCs. It is found that optimized energy level alignment can be achieved by thermal annealing. An interface dipole layer at the donor/acceptor interface is introduced by energy level realignment that assists charge generation by reducing geminate recombination so that the voltage loss is dramatically reduced, improving the performance of the all-PSCs.
关键词： Thermal Annealing,Voltage losses,Polymer solar cell,General design rule,Energy level alignment
更新于2025-09-19 17:13:59
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Enhanced performance of P3HT-based non-fullerene polymer solar cells by optimizing film morphology using non-halogenated solvent
摘要： Increasing research interests have been paid to developing efficient polymer solar cells by using integrating non-fullerene acceptors with poly(3-hexylthiophene) (P3HT), owing to the low-cost, promising performance and excellent stability. Here we systematically studied how processing solvents influence the overall performances of polymer solar cells using P3HT as the electron donor. It is very interesting to note that the devices processed with the non-halogenated solvent, 2-methylanisole in presence of 1-methylnaphthalene as solvent additive, exhibit reduced bimolecular and trap-assisted monomolecular recombination, facile charge extraction and enhanced charge carrier mobilities. Careful morphological investigation revealed that the optimizing crystallites, phase purity as well as nanofibrous structure is effective to the enhancement of charge generation and transport. It is also worth noting that these P3HT:O-IDTBR based devices processed with these non-halogenated solvents exhibited an impressive power conversion efficiency of 7.1% with a high fill factor of 75.09% on a device area of 0.05 cm2, and the efficiency remained 6.89% even in a device with large active layer area of 1 cm2, while also showing promising thermal stability. This study provides a new scope of processing P3HT based polymer solar cells by using non-halogenated solvents, which is compatible and has great promise for future applications.
关键词： large-area,polymer solar cell,poly(3-hexylthiophene),non-halogenated solvent,non-fullerene
更新于2025-09-19 17:13:59