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Naphthalene Diimide-Based Terpolymers with Controlled Crystalline Properties for Producing High Electron Mobility and Optimal Blend Morphology in All-Polymer Solar Cells
摘要： We report a series of new n-type random copolymers (P(NDI2OD-Se-Th x) where x = 0, 0.5, 0.7, 0.8, 0.9, 1.0) consisting of naphthalene diimide (NDI), selenophene-2,2’-thiophene (Se-Th), and seleno[3,2-b]thiophene (SeTh) to demonstrate their use in producing efficient all-polymer solar cells (all-PSCs) and organic field-effect transistors (OFETs). To investigate the effect of polymer crystallinity on the performance of all-PSCs and OFETs, we tuned the composition of the Se-Th and SeTh moieties in the P(NDI2OD-Se-Th x) polymers, resulting in enhanced crystalline properties with higher Se-Th ratio. Thus, the OFET electron mobility was increased with higher Se-Th ratio, exhibiting the highest value of 1.38×10?1 cm2 V?1 s?1 with P(NDI2OD-Se-Th 1.0). However, the performance of all-PSCs based on PBDB-T:P(NDI2OD-Se-Th x) showed a non-linear trend relative to the Se-Th ratio and the performance was optimized with P(NDI2OD-Se-Th 0.8) exhibiting the highest power coversion efficiency of 8.30%. This is attributed to the stronger crystallization-driven phase separation in all-polymer blends for higher Se-Th ratio. At the optimal crystallinity of P(NDI2OD-Se-Th 0.8) in all-PSCs, the degree of phase separation, domain purity and the electron mobility were optimized, resulting in enhanced charge generation and transport. Our works describe structure-property-performance relationships to design effective n-type polymers in terms of crystalline and electrical properties suitable for both efficient OFETs and all-PSCs.
关键词： organic field-effect transistors,seleno[3,2-b]thiophene,polymer crystallinity,n-type random copolymers,selenophene-2,2’-thiophene,charge generation,all-polymer solar cells,charge transport,naphthalene diimide
更新于2025-09-19 17:13:59
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4H-pyranylidene organic dyes for dye-sensitized solar cells: Twisted structures towards enhanced power conversion efficiencies
摘要： Five sensitizers bearing a 4H-pyranylidene moiety have been synthesized. The incorporation of a thiophene ring (with different substituents in its position 5), in the exocyclic double bond of the previously reported SFO-346, leads to twisted structures of type 2D-π-A and D–(π–A)2 that minimize the π-π stacking of the dyes on the photoanode. Theoretical calculations confirm the tridimensional structure of the molecules. Moreover, the different electronic nature and bulkiness of the substituents modulate the optical and electrochemical properties of the sensitizers. A power conversion efficiency of 7.68% was obtained when the thiophene was substituted with a tert-butyl group (dye 16), the highest value reported, so far, for dyes based on a 4H-pyranylidene. That efficiency is mainly due to the high open circuit voltage observed (0.729 V) without using anti-aggregating additives.
关键词： 4H-pyranylidene,Dye-sensitized solar cells,Open circuit voltage,Thiophene
更新于2025-09-19 17:13:59
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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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Exploring a fused 2-(thiophen-2-yl)thieno[3,2-b]thiophene (T-TT) building block to construct n-type polymer toward high performance all-polymer solar cells
摘要： In the field of all-polymer solar cells (all-PSCs), exploring new electron-donating units (D) to match with electron-accepting units (A) is an important subject to promote the performance of D-A type polymer acceptors. Herein, we developed a fused D unit 2-(thiophen-2-yl)thieno[3,2-b]thiophene (T-TT) derivated from the famous 2-(2-(thiophen-2-yl)vinyl)thiophene (TVT) unit. With classical naphthalene diimide (NDI) as A unit, the new D-A polymer PNDI-T-TT exhibits enhanced absorption coefficient, electron mobility and miscibility with donor polymer in comparison with the analogous PNDI-TVT polymer. These advantages can be attributed to the enlarged conjugation and reduced rotamers due to the fused T-TT unit, leading to stronger intermolecular interaction. When blending with the donor polymer PBDB-T, both NDI-based polymers can form better interpenetrating nanostructures than the corresponding blend films with donor polymer J71. Finally, PBDB-T:PNDI-T-TT device obtains a power conversion efficiency (PCE) of 6.1%, which is much higher than that of PBDB-T:PNDI-TVT device (4.24%). These results demonstrate that n-type polymer based on fused T-TT unit can ameliorate the absorption coefficient, molecular aggregation and charge carrier mobility and consequently achieve improved photovoltaic performance in comparison with classic TVT unit.
关键词： All-polymer solar cells,2-(2-(thiophen-2-yl)vinyl)thiophene,PBDB-T,naphthalene diimide,photovoltaic
更新于2025-09-19 17:13:59
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Elevated Photovoltaic Performance in Medium Bandgap Copolymers Composed of Indacenodi-thieno[3,2-b]thiophene and Benzothiadiazole Subunits by Modulating the ??-Bridge
摘要： Two random conjugated polymers (CPs), namely, PIDTT‐TBT and PIDTT‐TFBT, in which indacenodithieno[3,2‐b]thiophene (IDTT), 3‐octylthiophene, and benzothiadiazole (BT) were in turn utilized as electron‐donor (D), π‐bridge, and electron‐acceptor (A) units, were synthesized to comprehensively analyze the impact of reducing thiophene π‐bridge and further fluorination on photostability and photovoltaic performance. Meanwhile, the control polymer PIDTT‐DTBT with alternating structure was also prepared for comparison. The broadened and enhanced absorption, down‐shifted highest occupied molecular orbital energy level (EHOMO), more planar molecular geometry thus enhanced the aggregation in the film state, but insignificant impact on aggregation in solution and photostability were found after both reducing thiophene π‐bridge in PIDTT‐TBT and further fluorination in PIDTT‐TFBT. Consequently, PIDTT‐TBT‐based device showed 185% increased PCE of 5.84% profited by synergistically elevated VOC, JSC, and FF than those of its counterpart PIDTT‐DTBT, and this improvement was chiefly ascribed to the improved absorption, deepened EHOMO, raised μh and more balanced μh/μe, and optimized morphology of photoactive layer. However, the dropped PCE was observed after further fluorination in PIDTT‐TFBT, which was mainly restricted by undesired morphology for photoactive layer as a result of strong aggregation even if in the condition of the upshifted VOC. Our preliminary results can demonstrate that modulating the π‐bridge in polymer backbone was an effective method with the aim to enhance the performance for solar cell.
关键词： 2‐b]thiophene,random conjugated polymer,modulating π‐bridge,indacenodithieno[3,photovoltaic property
更新于2025-09-19 17:13:59
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Triphenylamine-based hole transporting materials with thiophene-derived bridges for perovskite solar cells
摘要： A triphenylamine-based compound containing benzoyl[1,2-b:4,5-b’]dithiophene (BDT) derivative (BTPA-2) has been synthesized and employed in FA0.85MA0.15PbI3 perovskite solar cells (PSCs) as the hole transporting material (HTM). The reference BTPA-1 containing thiophene bridge was also prepared for a comparative study. Compared to the thiophene unit in BTPA-1, the hexyloxy substituted BDT unit in BTPA-2 made the HOMO energy level lower. The more conjugated system with the BDT unit can improve the conductivity and hole mobility. The BTPA-1 and BTPA-2 based FA0.85MA0.15PbI3 PSCs showed the best power conversion efficiencies (PCE) of 12.76 % and 13.97 %, respectively. Larger Voc and higher Jsc for the BTPA-2 based PSC were attributed to its reduced interfacial recombination and more conjugated system compared to the BTPA-1 based PSCs. More hydrophobic property of BTAP-2 made its PSC exhibit better environmental stability than BTPA-1.
关键词： Thiophene,Perovskite solar cells,Water contact angle,Hole transporting materials,Triphenylamine
更新于2025-09-19 17:13:59
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?±-DTC <sub/>70</sub> fullerene performs significantly better than ?2-DTC70 as electron transporting material in perovskite solar cells
摘要： In this work, two new C70 isomers, α and β bis(2-(thiophen-2-yl)ethyl)-C70-fullerene mono-adducts (DTC70), were synthesized, characterized and used as electron transporting materials (ETMs) in perovskite solar cells (PSCs). Our results show that the α isomer improves both the Jsc and FF values of the devices, when compared to the results for the β-isomer and to those for phenyl-C70-butyric acid methyl ester (PC71BM), used as control. Devices based on α-DTC70 achieved a power conversion efficiency (PCE) of 15.9%, which is higher than that observed with PC71BM (15.1%).
关键词： perovskite solar cells,thiophene,Bingel adducts,fullerene derivatives,electron transporting materials
更新于2025-09-19 17:13:59
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Organic solar cells based on chlorine functionalized benzo[1,2-b:4,5-ba?2]difuran-benzo[1,2-c:4,5-ca?2]dithiophene-4,8-dione copolymer with efficiency exceeding 13%
摘要： Benzo[1,2-b:4,5-b′]dithiophene (BDT) has been widely used to construct donor-acceptor (D-A) copolymers in organic solar cells (OSCs). However, benzo[1,2-b:4,5-b′]difuran (BDF), an analogue of BDT, has received less attention than BDT. The photovoltaic performance of BDF copolymers has lagged behind that of BDT copolymers. Here, we designed and synthesized two BDF copolymers, PBF1-C and PBF1-C-2Cl. PBF1-C-2Cl, which is composed of BDF and benzo[1,2-c:4,5-c′]dithiophene-4,8-dione connected by a chlorinated thiophene π-bridge, displays a low-lying highest occupied molecular orbital energy level, which helps in yielding a high open-circuit voltage (Voc) in OSCs. As a result, when blended with Y6, PBF1-C-2Cl-based devices showed a high Voc of 0.83 V and a power conversion efficiency (PCE) of 13.10%. To the best of our knowledge, the PCE of 13.10% is among the highest efficiency values for OSCs based on BDF copolymers.
关键词： chlorinated thiophene,π-bridge,benzo[1,2-c:4,5-c′]dithiophene-4,8-dione,benzo[1,2-b:4,5-b′]difuran,organic solar cells
更新于2025-09-19 17:13:59
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Tuning opto-electronic properties of alkoxy-induced based electron acceptors in infrared region for high performance organic solar cells
摘要： Limitations of fullerene-based acceptors for organic solar cell have driven the scientific community to design and synthesize non-fullerene acceptors. In this regard, we have designed four new molecules designated here S1-S4 containing Alkoxy-Induced Naphtho-dithiophene donor unit and 2-(5,6-difluoro-2-methylene-3-xo-2,3-dihydrinden-1-ylidene)malonoitrile acceptor moiety attached with different bridge units. The electronic and optical properties of the designed molecules S1-S4 are compared with the recently reported reference molecule R. The bridge units are, thiophene (S1), 2-fluorothiophene (S2), 2-(thiophe-2-yl)thiophene (S3) and 2-(4-fluorothiophen-2-yl)thiophene (S4). The designed molecule S3 shows absorption maximum in near infra-red (NIR) region at 830.0 nm and 910.6 nm in gas phase and chloroform solvent, respectively. The energy gaps of designed molecules are lower than that of the reference R, which reveal high charge transfer for the designed molecules. Among all, S3 has the lowest energy gap (1.68 eV). Open circuit voltages (Voc) calculation are performed with well-known PTB7-Th donor. Voc of all the molecules are higher than R where the maximum Voc of 1.92V is calculated for S2. Low reorganization energies of our designed molecule reflect high charge transfer rate with respect to R. Among all designed molecules, S3 has the highest electron mobility.
关键词： Alkoxy induced,Reorganization energy,Transition density matrix,Non-fullerene acceptor,Thiophene,Charge Transfer,Open circuit voltages
更新于2025-09-19 17:13:59
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Charge transfer in Nanowire-Embedded PEDOT:PSS and Planar Heterojunction Solar Cells
摘要： Hybrid metallic nanowires-embedded, highly conductive poly(3,4-ethylenedioxy thiophene):polystyrenesulfonate (PEDOT:PSS) with synergetic properties is indispensable for enhancing the performances of conductive polymer-based electronic devices. Here we report embedment of silver nanowires (AgNWs), with diameter ~100 nm and a high concentration (500 mg/ml) of nanowires dispersed in either ethanol or isopropanol, in PEDOT:PSS and compare the effects of the nanowire-dispersing solvents as well as its thicker diameter and high concentration on the overall properties, and particularly its charge transfer characteristics and planar heterojunction solar cell (HSC) properties. Furthermore, electrostatic force microscopy is applied to elucidate the direct charge transfer from AgNWs to the PEDOT:PSS matrix. The AgNW-embedded PEDOT:PSS-based planar HSCs show a very high open-circuit voltage of over 638 mV and a high power conversion efficiency greater than 15.3%, and without any significant influence from the AgNWs dispersing solvents. While charge transfer in PEDOT:PSS without AgNWs occurs through the conducting PEDOT grains, enhanced charge transfer is realized in AgNW-embedded PEDOT:PSS with charge transport from PEDOT grains to AgNWs and then to PEDOT grains before reaching the top electrode in the HSC. The AgNW-embedded PEDOT:PSS hybrid materials pave a simple way to enhance the charge transfer performance in not only HSCs but also other hybrid or heterojunction electronics.
关键词： heterojunction solar cell,poly(3,4-ethylenedioxy thiophene):polystyrenesulfonate or PEDOT:PSS,silver nanowire,Conducting polymer,electrostatic force microscopy,charge transfer
更新于2025-09-19 17:13:59