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What can we learn from model systems: Impact of polymer backbone structure on performance and stability of organic photovoltaics
摘要： We report the synthesis and extensive investigation of a broad family of novel (X-DADAD)n conjugated polymers with different X building blocks. It was shown that variation of X block in polymer backbone represents an efficient approach for tuning the polymer optical properties, frontier energy levels, charge transport characteristics as well as thin-film morphology and photovoltaic characteristics. Decent power conversion efficiencies (5.1–5.7%) were achieved for solar cells based on the polymers comprised of dibenzosilole (P2) and carbazole (P3) units. Polymers P2 and P3 showed impressive indoor and outdoor stability in solar cells while clearly outperforming common benchmark materials. In the view of the obtained results, the designed (X-DADAD)n polymers can be considered as promising semiconductor materials for stable organic photovoltaics.
关键词： Operational stability,Organic solar cells,Thiophene,Conjugated polymers,Benzothiadiazole
更新于2025-09-19 17:13:59
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High-Performance Ambient-Condition-Processed Polymer Solar Cells and Organic Thin-Film Transistors
摘要： Large-scale commercial synthesis of bulk-heterojunction (BHJ) solar cell materials is very challenging and both time and energy consuming. Synthesis of π-conjugated polymers (CPs) with uniform batch-to-batch molecular weight and low dispersity is a key requirement for better reproducibility of high-efficiency polymer solar cells. Herein, a conjugated polymer (CP) PTB7-Th, well known for its high performance, has been synthesized with high molecular weight and low dispersity in a closed microwave reactor. The microwave reaction procedure is known to be more controlled and consumes less energy. The precursors were strategically reacted for different reaction time durations to obtain the optimum molecular weight. All different CPs were well characterized using 1H NMR, gel permeation chromatography (GPC), UV?vis, photoluminescence (PL), electron spin resonance (ESR), and Raman spectroscopy, whereas the film morphology was extensively studied via atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXRD) techniques. The effect of molecular weight on a conventional BHJ solar cell with PC71BM acceptor was investigated to derive systematic structure?property relationships. The CP obtained after 35 min of reaction time and integrated into BHJ devices under ambient conditions provided the best performance with a power conversion efficiency (PCE) of 8.09%, which was quite similar to the results of CPs synthesized via a thermal route. An enhanced PCE of 8.47% was obtained for the optimized polymer (35 min microwave reaction product) when device fabrication was carried out inside a glovebox. The organic thin-film transistor (OTFT) device with the microwave-synthesized CP displayed better hole mobility (0.137 cm2 V?1 s?1) as compared to that with the thermally synthesized CP. This study also proved that the device stability and reproducibility of the microwave-synthesized CP were much better and more consistent than those of the thermally developed CP.
关键词： microwave reactor,π-conjugated polymers,organic thin-film transistors,polymer solar cells,bulk-heterojunction
更新于2025-09-19 17:13:59
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Enhanced Performance and Stability of TiO <sub/>2</sub> ‐Nanoparticles‐Based Perovskite Solar Cells Employing a Cheap Polymeric Surface Modifier
摘要： Interface engineering of TiO2 nanoparticles (NPs)-based perovskite solar cells (PVSCs) is often necessary to facilitate the extraction and transport of charge carriers. In this work, poly[{9,9-bis[3’-(N,N-dimethyl)propyl]-2,7-fluorene}-alt-2,7-(9,9-dioctyl-fluorene)] (PFN) and polystyrene (PS) are demonstrated to be effective surface modifiers of the TiO2 NPs electron-transporting layer in n-i-p PVSCs. The low-cost insulating polymer PS performs better than the PFN conjugated polymer owing to its high film quality, low surface energy and insulating characteristics. A peak power conversion efficiency (PCE) of 15.09 % with an open-circuit voltage (VOC) of 1.05 V and a PCE of 17.13 % with an ultrahigh VOC of 1.18 V is achieved with TiO2 NPs/PS-based PVSCs using poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and spiro-OMeTAD, respectively, as the hole-transporting material.
关键词： interface modification layers,plastics,electron-transporting layers,conjugated polymers,TiO2 nanoparticles
更新于2025-09-19 17:13:59
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13.2% Efficiency of Organic Solar Cells by Controlling Interfacial Resistance resulted from Well-distributed Vertical Phase Separation
摘要： Two strategies were investigated to improve the efficiency of organic solar cells (OSCs) with the aim of controlling the interfacial resistance in the devices: the use of a ternary active layer and the introduction of conjugated polymers. The ternary active layer was formed by introducing PC71BM between a high-performance non-fullerene photoactive material P(Cl-Cl)(BDD=0.2) and the IT-4F-based binary active layer, thereby reducing the interfacial resistance between the donor and acceptor via vertical phase separation. Furthermore, the introduction of the conjugated polymer PFN-Br created a well-dispersed separation attributable to enhancement of the interfacial contact with the active layer, and simultaneous reduction of the interfacial resistance. Consequently, the synergetic effect of the ternary active layer and PFN-Br enhanced the short-circuit current density (JSC) and fill factor (FF) to realize power conversion efficiency (PCE) of 13.2%.
关键词： Power conversion efficiency,Interfacial resistance,Conjugated polymers,Ternary active layer,Organic solar cells
更新于2025-09-19 17:13:59
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Indoor Photovoltaics: Photoactive Material Selection, Greener Ink Formulations, and Slot-Die Coated Active Layers
摘要： Strong visible light absorption is essential to achieve high power conversion efficiency in indoor organic photovoltaics (iOPVs). Here, we report iOPVs that exhibit high efficiency with high voltage under excitation by low power indoor lighting. Inverted type organic photovoltaic devices with active layer blends utilizing the polymer donor PPDT2FBT paired with fullerene, perylene diimide, or ring-fused acceptors that are 6.5-9.1% efficient under 1 sun are demonstrated to reach efficiencies from 10-17% under an indoor light source. This performance transcends that of a standard silicon photovoltaic device. Moreover, we compared iOPVs with active layers both spin-cast and slot-die cast from non-halogenated solvents and demonstrate comparable performance. This work opens a path towards high efficiency iOPVs for low power electronics.
关键词： Organic Photovoltaics,Perylene Diimide Dyes,Conjugated Polymers,Roll-to-Roll Compatible Coating,Green Solvent Processing
更新于2025-09-16 10:30:52
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A Long π-Conjugated Poly-para-Phenylene-Based Polymeric Segment of Single-Walled Carbon Nanotubes
摘要： Conjugated polymers have attracted much attention for many years and have applications in various organic devices. Carbon nanotubes can be considered as all-carbon tube-shaped conjugated polymers containing only sp2-bonded atoms, which play an important role in nanotechnology and nanoelectronics. So far, no study has reported the realization of long π-conjugated polymers as diameter-specified carbon nanotube segments. Herein, we report the first synthesis of a π-conjugated polymeric segment (PS1) of armchair single-walled carbon nanotubes (SWCNTs). PS1 is achieved by a rationally designed synthesis of a bifunctionalized cyclo-para-phenylene monomer, followed by inserting these ring-shaped units into the conjugated poly-para-phenylene backbone. PS1 was fully characterized by gel permeation chromatography (GPC) combined with NMR, FTIR, and Raman spectra. Possessing unique structural and physical properties, this long π-extended polymer PS1 can provide new insight for the development of bottom-up syntheses of uniform carbon nanotube segments and potential applications in electron- and hole-transport devices.
关键词： electron-transport devices,bottom-up synthesis,poly-para-phenylene,carbon nanotubes,π-conjugated polymers,hole-transport devices
更新于2025-09-16 10:30:52
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Effect of Top Channel Thickness in Near Infrared Organic Phototransistors with Conjugated Polymer Gate-Sensing Layers
摘要： Here, we report the thickness effect of top channel layers (CLs) on the performance of near infrared (NIR)-detecting organic phototransistors (OPTRs) with conjugated polymer gate-sensing layers (GSLs). Poly(3-hexylthiophene) (P3HT) was employed as a top CL, while poly[{2,5-bis-(2-octyldodecyl)-3,6-bis-(thien-2-yl)-pyrrolo[3,4-c]pyrrole-1,4-diyl}-co-{2,2-(2,1,3-benzothiadiazole)-5,5-diyl}] (PODTPPD-BT) was used as a GSL. The thickness of P3HT CLs was varied from 10 to 70 nm. Three different wavelengths of NIR light (λ = 780, 905, and 1000 nm) were introduced and their light intensity was fixed to 0.27 mW cm?2. Results showed that all fabricated devices exhibited typical p-channel transistor behaviors and the highest drain current in the dark was obtained at the P3HT thickness (t) of 50 nm. The NIR illumination test revealed that the NIR photoresponsivity (RC) of GSL-OPTRs could be achieved at t = 50 nm irrespective of the NIR wavelength. The maximum RC of the optimized devices (t = 50 nm) reached ca. 61% at λ = 780 nm and ca. 47% at λ = 1000 nm compared to the theoretical maximum photoresponsivity.
关键词： near infrared,organic phototransistors,channel layers,conjugated polymers
更新于2025-09-16 10:30:52
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Broadband polymer photodetectors with a good trade-off between broad response and high detectivity by using combined electron-deficient moieties
摘要： High-performance broadband photodetectors based on low-bandgap conjugated polymers are scarce due to a trade-off between the photoresponse range and device performance. In this work, the polymers with structural features responsible for both broad response and high detectivity are realized by using the combined electron deficient moieties at the molecular level. Based on the electron-deficient diketopyrrolopyrrole (DPP) and benzothiadiazole (BT), the combined units of DPP-DPP and DPP-BT-DPP are deemed more electron deficient and were successfully incorporated into the corresponding polymers. The arrangement of electron deficient moieties in the polymer mainchain were found to be able to greatly affect the absorption profile, energy level, molecular stacking, and blend film morphology. Consequently, the photodetector based on the polymer with DPP-BT-DPP acceptor exhibited the D* value of over 1012 Jones in the spectral region of 320–930 nm under -0.1 V bias.
关键词： low-bandgap conjugated polymers,electron deficient moieties,high detectivity,DPP,broadband photodetectors,BT
更新于2025-09-16 10:30:52
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Recent advances in circularly polarized electroluminescence based on organic light-emitting diodes
摘要： Since the first attempt that was made to obtain direct circularly polarized (CP) light from OLEDs by Meijer et al. in 1997, considerable efforts have been devoted to the development of circularly polarized organic light-emitting diodes (CP-OLEDs), particularly in the recent years. Circularly polarized electroluminescence (CPEL) based on OLEDs has attracted increasing interest for its efficient ability to generate CP light directly and wide potential applications in 3D displays, optical data storage, and optical spintronics. In this review, we systematically summarize the recent progress in chiral emitter based OLEDs with CPEL properties including CPEL based on chiral conjugated polymers, CPEL based on chiral metal complexes, and CPEL based on chiral simple organic molecules, especially chiral thermally activated delayed fluorescence (TADF) molecules. We believe that this review will provide a promising perspective of chiral emitter based OLEDs with CPEL properties for a broad range of scientists in different disciplinary areas and attract a growing number of researchers to this fast-growing research field.
关键词： chiral simple organic molecules,circularly polarized electroluminescence,thermally activated delayed fluorescence,chiral conjugated polymers,organic light-emitting diodes,chiral metal complexes
更新于2025-09-16 10:30:52
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Modulation of Building Block Size in Conjugated Polymers with D–A Structure for Polymer Solar Cells
摘要： D?A conjugated polymers have played critical roles in recently reported nonfullerene acceptors-based polymer solar cells (NF-PSCs) with high performance. Although the molecular design of the D?A polymers is getting more mature, there are still some fundamental unknowns to be unveiled. Here, three new D?A polymers with varied conjugated length for the D-units in their backbones, namely, PDB-1, PDB-2, and PDB-3, were designed, synthesized, and characterized. It was demonstrated that a longer D-unit leads to stronger interchain interaction and higher hole mobility for pristine polymer films. While blending with IT-4F to fabricate photoactive layers in PSCs, it was found that the domain purity, aggregation size, and π?π stacking effect of the polymers can be greatly affected by the D-unit size. Compared to polymers with shorter D-units, for the polymer with the largest D-units (PDB-3), hole and electron transport channels can be much more easily formed in the blend films. Interestingly, the highest efficiency was obtained in the PSCs based on a PDB-2:IT-4F blend, in which PDB-2 shows similar D-unit size to the polymers with state-of-the-art high photovoltaic performance. The correlations between the molecular structure and photovoltaic property of PDB-x polymers demonstrate that the modulation of building block size is an important method for designing high-performance D?A conjugated polymers for PSCs.
关键词： polymer solar cells,nonfullerene acceptors,D?A conjugated polymers,building block size,photovoltaic performance
更新于2025-09-16 10:30:52