A novel phenylenevinylene copolymer (JP) with 4,7-dithien-5-yl-2,1,3-benzodiathiazole (DTBT) moiety along the backbone and di(p-tolyl)phenylamine (p-TPA) unit as side groups was synthesized and applied in polymer solar cells (PSCs). Introduction of DTBT and p-TPA moieties is beneficial to lowering the band gap, broadening the absorption spectrum and improving the photovoltaic properties of the copolymer. The effects of DTBT and p-TPA moieties on the thermal, photophysical, electrochemical and photovoltaic properties of the copolymer are investigated. The bulk heterojunction polymer solar cells based on JP and PC61BM (1:3, w/w) showed a maximum power conversion efficiency of 1.09% with an open-circuit voltage of 0.75 V, a short-circuit current of 3.69 mA cm−2, and a fill factor of 0.50. 相似文献
A series of D–T–A–T–D derivatives (D, electron-donating moiety; T, π-conjugated linker; A, electron-acceptor moiety) with seven electron donor moieties and various electron abilities are designed to investigate the influence of the donor on photophysical properties for small-molecule organic photovoltaic solar cells. The 4,8-dimethoxybenzodithiophene (D1), triphenyldsramine (D2), 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline (D3), 9,9-dimethyl-9H-fluorene (D4), 9-methyl-9H-carbazole (D5), 4-methyl-4H-dithieno-pyrrole (D6), and 4,4-dimethyl-4H-cyclopenta-dithiophene (D7) are adopted as the electron donor moiety. The BDTC (buta-1,3-diene-1,1,4,4-tetracarbonitrile) is used for the A moiety, and the thiophene (T) is used for the π-conjugated linker. The optimized structure of D–T–A–T–D derivatives exhibits the bend molecular conformation due to the steric effect within the A moiety. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies of these derivatives are dependent on the electron donating ability of D, which influences the open-circuit voltage and driving force. Reorganization energy suggests that these derivatives are good hole-transporting type materials. Projected density of state analysis demonstrates that in the HOMO, the electron density distribution is delocalized on the terminal D and T moieties, while in the LUMO, the electron density distribution is localized mainly on the A moiety. The maximum absorption peak, which has relatively high light harvesting efficiency, is due to the π to π* transition and can be tuned by the electron-donating ability and the resonance energy of the D moiety. The bend D6–T–A–T–D6/D7–T–A–T–D7 derivatives with D moiety of 4-methyl-4H-dithieno-pyrrole (D6) and 4,4-dimethyl-4H-cyclopenta-dithiophene (D7) are good candidates as electron donor materials for SM-OPV. 相似文献
An alternating narrow bandgap conjugated copolymer (PICZ‐DTBT, Eg= 1.83 eV) derived from 5,11‐di(9‐heptadecanyl)indolo[3,2‐b]carbazole and 4,7‐di(thieno[3,2‐b]thien‐2‐yl)‐2,1,3‐benzothiadiazole (DTBT), was prepared by the palladium‐catalyzed Suzuki coupling reaction. The resultant polymer absorbs light from 350–690 nm, exhibits two absorbance peaks at around 420 and 570 nm and has good solution processibility and thermal stability. The highest occupied molecular orbital (HOMO) energy level and lowest unoccupied molecular orbital (LUMO) level of the copolymer determined by cyclic voltammetry were about −5.18 and −3.35 eV, respectively. Prototype bulk heterojunction photovoltaic cells from solid‐state composite films based on PICZ‐DTBT and [6,6]‐phenyl‐C71 butyric acid methyl ester (PC71BM), show power conversion efficiencies up to 2.4% under 80 mW · cm−2 illumination (AM1.5) with an open‐circuit voltage of Voc = 0.75 V, a short current density of Jsc = 6.02 mA · cm−2, and a fill factor of 42%. This indicates that the copolymer PICZ‐DTBT is a viable electron donor material for polymeric solar cells.
In this study, two ligands and their ruthenium complexes are synthesized and their photovoltaic properties for dye-sensitized solar cells (DSSCs) of new substances substituted by 4,5-diazafluorenone-9-hydrazone groups is investigated. The structures of the compounds are determined by FTIR, UV-Vis, HNMR, CNMR, and MS spectroscopic techniques. The photovoltaic and electrochemical properties of these compounds are investigated and the applicability in DSSCs as photo sensitizers is studied. Photovoltaic cell efficiencies (PCEs) of the devices are in the range 0.08-1.54% under simulated AM 1.5 solar irradiation of 100 mW/cm2, and the highest open-circuit voltage (Voc) reaches 0.43 V. When the photovoltaic performance of the DSSC devices is compared, it indicates that PCEs assume the following: P1–Ru > > P2–Ru > P1 > P2. The PCE value of 1.54% is obtained with DSSC based on P1–Ru under AM irradiation (100 mW/cm2). DSSC based on the P1–Ru produced efficiency of 1.54% whereas DSSC-based P1 exhibits the device performance with an efficiency of 0.08% under illumination. These results suggest that a larger π-conjugated bridge and a richer electron donor of P1–Ru are beneficial for the photovoltaic performance of DSSC. 相似文献
New efficient push–pull organic semiconductors comprising of the bis(9,9-dimethyl-9H-fluoren-2-yl)aniline (bisDMFA) donor and the various acceptors such as NO2, DCBP, and TCF, which were linked with bithiophene or vinyl bithiophene π-conjugation bridges, were synthesized, and their photovoltaic characteristics were investigated in solution-processed small molecule organic solar cells (SMOSCs). The intramolecular charge transfers of these materials were effectively appeared in between bisDMFA donor and acceptors, depending on the electron-withdrawing strength of acceptors. The organic semiconductors having NO2 and DCBP acceptors exhibited the most efficient photovoltaic performance, showing power conversion efficiency (PCE) of 1.98% (±0.17) and 2.01% (±0.21), respectively. When the TiOx thin layer was treated on photoactive layer, the organic semiconductor having NO2 showed the best PCE of 2.70% with short circuit current of 8.19 mA/cm2, fill factor of 0.40, and open circuit voltage of 0.83 V in SMOSC devices. 相似文献
A high performance polymer solar cells(PSCs) based on polymer donor PM6 containing fluorinated thienyl benzodithiophene unit and n-type organic semiconductor acceptor IT-4 F containing fluorinated end-groups were developed. In addition to complementary absorption spectra(300–830 nm) with IT-4 F, the PM6 also has a deep HOMO(the highest occupied molecular) level(-5.50 e V), which will lower the open-circuit voltage(V_(oc)) sacrifice and reduce the E_(loss) of the IT-4 F-based PSCs. Moreover, the strong crystallinity of PM6 is beneficial to form favorable blend morphology and hence to suppress recombination. As a result, in comparison with the PSCs based on a non-fluorinated D/A pair of PBDB-T:ITIC with a medium PCE of 11.2%, the PM6:IT-4 Fbased PSCs yielded an impressive PCE of 13.5% due to the synergistic effect of fluorination on both donor and acceptor, which is among the highest values recorded in the literatures for PSCs to date. Furthermore, a PCE of 12.2% was remained with the active layer thickness of up to 285 nm and a high PCE of 11.4% was also obtained with a large device area of 1 cm~2. In addition, the devices also showed good storage, thermal and illumination stabilities with respect to the efficiency. These results indicate that fluorination is an effective strategy to improve the photovoltaic performance of materials, as well as the both fluorinated donor and acceptor pair-PM6:IT-4 F is an ideal candidate for the large scale roll-to-roll production of efficient PSCs in the future. 相似文献
As a novel class of materials, D–A conjugated macrocycles hold significant promise for chemical science. However, their potential in photovoltaic remains largely untapped due to the complexity of introducing multiple donor and acceptor moieties into the design and synthesis of cyclic π-conjugated molecules. Here, we report a multiple D–A ring-like conjugated molecule ( RCM ) via the coupling of dimer molecule DBTP-C3 as a template and thiophenes in high yields. RCM exhibits a narrow optical gap (1.33 eV) and excellent thermal stability, and shows a remarkable photoluminescence yield (ΦPL) of 11.1 % in solution, much higher than non-cyclic analogues. Organic solar cell (OSC) constructed with RCM as electron acceptor shows efficient charge separation at donor-acceptor band offsets and achieves a power conversion efficiency (PCE) of 14.2 %-approximately fourfold higher than macrocycle-based OSCs reported so far. This is partly due to low non-radiative voltage loss down to 0.20 eV and a high electroluminescence yield (ΦEL) of 4×10−4. Our findings emphasize the potential of D–A cyclic conjugated molecules in advancing organic photovoltaic technology. 相似文献
Spirofluorene (SF) and benzo[d][1,2,3]triazole (BTA) have been considered as promising building blocks to construct n‐type photovoltaic materials. Herein, three new small molecule acceptors (SMAs) named BTA21 , BTA23 and BTA27 with the structure of A2 = A1‐D‐A1 = A2 have been designed, in which SF and BTA were used as a central unit of D and bridged acceptor unit of A1, respectively. In addition, 3‐ethylrhodanine, 2‐(3‐ethyl‐4‐ oxothiazolidin‐2‐ylidene)malononitrile and malononitrile were chosen as terminal acceptor units to modulate the properties of the final SMAs. Three SMAs show wide optical band gaps (Eg) of 2.19, 2.15 and 2.21 eV, respectively, with gradually down‐shift of the lowest unoccupied molecular orbital (LUMO) levels in the order of BTA21 , BTA23 and BTA27 depending on the electron‐withdrawing capability of terminal acceptor units. BTA21 shows great advantages with respect to donor poly(3‐hexylthiophene) (P3HT) over BTA23 and BTA27 , such as well energy‐level matching, complementary absorption and proper morphology. Concequently, P3HT: BTA21 shows the best power conversion efficiency (PCE) value of 3.28% with an open‐circuit voltage (VOC) of 1.02 V, a short‐circuit current (JSC) of 5.45 mA·cm–2 and a fill factor (FF) of 0.59. These results indicate that the terminal acceptor group end‐capped in SMAs plays a significant role in controlling their optical, electronic, and photovoltaic properties. 相似文献
A partially hydrophobic carbazole ligand ((Im+)2Cz: 2,2′‐(9‐ethyl‐9 H‐carbazole‐3,6‐diyl)bis(ethyne‐2,1‐diyl)bis(1,3‐dimethyl‐1 H‐imidazol‐3‐ium)) adopts two different binding states (binding states I and II) in its interactions with calf‐thymus (ct‐) DNA. Two distinct binding states were identified by biphasic UV/Vis and circular dichroism (CD) spectral changes during the titration of DNA into the carbazole ligand. At low concentrations of ct‐DNA, (Im+)2Cz binds to nearly every part of ct‐DNA (binding state I). By contrast, an increased concentration of ct‐DNA results in a switch in the DNA‐binding state, so that the ligands are bound per five DNA base pairs. Similarly, a monocationic carbazole ligand (Im+Cz: 2‐((6‐bromo‐9‐ethyl‐9 H‐carbazol‐3‐yl)ethynyl)‐1,3‐dimethyl‐1 H‐imidazol‐3‐ium) also shows biphasic UV/Vis spectral changes during the titration of ct‐DNA into Im+Cz, which suggests two different binding states of the Im+Cz ligand with ct‐DNA. The stepwise equilibrium of the ligand–DNA‐complex formation is capable of switching the thermal stability of ct‐DNA, as well as the enzymatic activity of deoxyribonuclease (DNase I). In binding state I, the (Im+)2Cz ligands interact with nearly every base pair in ct‐DNA and stabilize the double‐helix structure, which results in a larger increase in the melting temperature of the ct‐DNA than that observed with binding state II. On the other hand, the (Im+)2Cz ligand significantly reduces the enzymatic activity of DNase I in binding state I, although the enzymatic activity is recovered once the binding state of the ligand–DNA complex is changed to binding state II. The (Im+)2Cz ligand was also employed as a binder for G‐quadruplex DNA. In contrast to the stepwise complex formation between (Im+)2Cz and ct‐DNA, (Im+)2Cz shows a monotonous UV/Vis spectral response during the titration of G‐quadruplex DNA into (Im+)2Cz, which suggests a single binding state for (Im+)2Cz with G‐quadruplex DNA. 相似文献
Two new low‐bandgap block copolymers derived from dithienylbenzothiadiazole (DTBT) and different electron‐rich functional groups (dioctoxyl benzene and N‐octyl‐diphenylamine), poly(1,4‐dioctoxyl‐2,5‐divinylbenzene‐co‐4,7‐dithiophene‐2′‐yl‐2,1,3‐benzothiadiazole) (PPV‐DTBT), poly(3,8‐divinyl‐N‐octyl‐diphenylamine‐co‐4,7‐dithiophene‐2′‐yl‐2,1,3‐benzothiadiazole) (PDPAV‐DTBT), were synthesized by Heck cross‐coupling polymerization. PPV‐DTBT and PDPAV‐DTBT are easily soluble in common organic solvents such as o‐dichlorobenzene and chloroform. DSC and TGA results indicate that these copolymers possess good thermal stabilities. PPV‐DTBT and PDPAV‐DTBT films exhibit broad absorption bands at 300–765 nm (with an optical bandgap of 1.62 eV) and 300–733 nm (with an optical bandgap of 1.69 eV), respectively. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of PPV‐DTBT were estimated by cyclic voltammetry to be −5.43 and −3.74 eV, respectively, and the HOMO and LUMO of PDPAV‐DTBT were −5.37 and −3.7 eV, respectively. Preliminary photovoltaic cells based on the composite structure of ITO/PEDOT: PSS/PPV‐DTBT:PCBM (1: 2, w/w)/Al showed an open‐circuit voltage of 0.75 V, a power conversion efficiency of 0.6%, and a short circuit current of 1.7 mA · cm−2.
