| 1. |
- An, Jincheng, et al.
(författare)
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Fine-Tuning by Triple Bond of Carbazole Derivative Dyes to Obtain High Efficiency for Dye-Sensitized Solar Cells with Copper Electrolyte
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : NLM (Medline). - 1944-8244 .- 1944-8252. ; 12:41, s. 46397-46405
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Tidskriftsartikel (refereegranskat)abstract
- Three novel dyes consisting of a 5,8,15-tris(2-ethylhexyl)-8,15-dihydro-5H-benzo[1,2-b:3,4-b':6,5-b″]tricarbazole (BTC) electron-donating group and a 4,7-bis(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (BTBT) π-bridge with an anchoring group of phenyl carboxyl acid were synthesized and applied in dye-sensitized solar cells (DSCs).The AJ202 did not contain any triple bonds, the AJ201's ethynyl group was inserted between the BTC and BTBT units, and the AJ206's ethynyl group was introduced between the BTBT moiety and the anchor group. The inclusion and position of the ethynyl linkage in the sensitizer molecules significantly altered the electrochemical properties of these dyes, which can fine-tune the energy levels of the dyes. The best performing devices contained AJ206 as a sensitizer and a Cu(I/II) redox couple, which resulted in a power conversion efficiency (PCE) up to 10.8% under the standard AM 1.5 G illumination, which obtained PCEs higher than those from the devices that contained AJ201 (9.2%) and AJ202 (9.7%) under the same conditions. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels of the sensitizers were tuned to be well-suited for the Cu(I/II) redox potential and the Fermi level of TiO2. The innovative synthesis of a tricarbazole-based donor moiety in a sensitizer used in combination with a Cu(I/II) redox couple has resulted in relatively high PCEs.
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| 2. |
- Deng, Zijian, et al.
(författare)
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Helical Copper Redox Mediator with Low Electron Recombination for Dye-Sensitized Solar Cells
- 2021
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 9:15, s. 5252-5259
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Tidskriftsartikel (refereegranskat)abstract
- Redox mediators play a major role in determining the photocurrent and photovoltage in dye-sensitized solar cells (DSSCs). Copper complexes are a good option for redox mediators but suffer from electron recombination. The traditional method is to add 4-(tert-butyl)pyridine (TBP) to the electrolyte, which is coordinated with the empty orbit of Ti, thereby slowing down the oxidized mediator's ability to capture electrons. However, this strategy will result in competitive coordination between the redox mediator and TBP, decreasing the stability of the device. In this study, two helical copper(I) complexes are synthesized and applied to TBP-free solar cells. La (1,3-bis(2,2'-bipyridin-6-yloxy)propane) and Lb (1,3-bis[(6'-methyl-2,2'-bipyridin-6-yl)oxy]propane) tend to form double-stranded helicates ([Cu-2(Ln)(2)](2+), n = a, b) rather than mononuclear complexes ([Cu(Ln)](+), n = a, b). To facilitate quantitative analysis of the complexes, Cu(I)Ln and Cu(II)Ln (n = a, b) are used as molecular formulae. (CuLa)-La-I and Cu(I)Lb are characterized by electrospray mass spectroscopy, H-1 NMR spectroscopy, and electrochemistry. J-V measurement shows that both V-oc and J(sc) increase with the increase of (CuLa)-La-I concentration (below 0.1 M), and the best power conversion efficiency is 8.2%. The relationship between Cu(I) concentration and recombination for further study was measured by IMVS.
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| 3. |
- Teng, Chao, et al.
(författare)
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Influence of Triple Bonds as pi-Spacer Units in Metal-Free Organic Dyes for Dye-Sensitized Solar Cells
- 2010
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:25, s. 11305-11313
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Tidskriftsartikel (refereegranskat)abstract
- Four metal-free organic sensitizers (TC101-TC104) with triple bonds in pi-spacers and five reference dyes (TC, TC105, TPC1, D5, and TH208) without triple bonds were applied in dye-sensitized solar cells to study the influence of triple bonds as pi-spacer units on their photoelectrochemical properties and dye-sensitized solar cells (DSCs) performance. Results show that the introduction of triple bond could red-shift the dye's absorption spectrum due to the enhancement of the pi-spacer. However, the spectrum red-shift is much less than that of the introduction of double bond because of more electronegativity of triple bond. The incident photon-to-current conversion efficiency reveals that the electron transfer yield (Phi(nu)(ET)) of DSCs becomes larger with the introduction of triple bond. Electrochemical impedance spectroscopy analysis reveals that the introduction of triple bond almost does not change the electron lifetimes in TiO2 films but decreases the effective diffusion lengths.
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| 4. |
- Teng, Chao, et al.
(författare)
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Molecular Design of Anthracene-Bridged Metal-Free Organic Dyes for Efficient Dye-Sensitized Solar Cells
- 2010
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:19, s. 9101-9110
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Tidskriftsartikel (refereegranskat)abstract
- A series of metal-free organic dyes bridged by anthracene-containing pi-conjugations were designed and synthesized as new chromophores for the application of dye-sensitized solar cells (DSCs). Detailed investigations on the relationship between the dye structures, photophysical properties, electrochemical properties, and performances of DSCs are described. With the introduction of the anthracene moiety, together with a triple bond for the fine-tuning of molecular planar configurations and to broaden absorption spectra, the short-circuit photocurrent densities (J(sc)) and open-circuit photovoltages (V-oc) of DSCs were improved to a large extent. The improvement of J(sc) is attributed to much broader absorption spectra of the dyes with the anthracene moiety. Electrochemical impedance spectroscopy (EIS) analysis reveals that the introduction of the anthracene moiety suppresses the charge recombination arising from electrons in TiO2 films with I-3(-) ions in the electrolyte, thus improving V-oc considerably. On the basis of optimized molecular structures and DSC test conditions, the dye TC501 shows a prominent solar energy conversion efficiency (eta) up to 7.03% (J(sc) = 12.96 mA . cm(-2), V-OC = 720 mV, ff = 0.753) under simulated AM 1.5 irradiation (100 mW . cm(-2)).
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| 5. |
- An, Jincheng, et al.
(författare)
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Thiophene-fused carbazole derivative dyes for high-performance dye-sensitized solar cells
- 2021
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 88
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Tidskriftsartikel (refereegranskat)abstract
- Two novel dyes that are similar in chemical structure, except for different donor units, AJ301and AJ303 were synthesized, characterized and applied as sensitizers in dye-sensitized solar cells (DSSCs). Both dyes exhibited a wide absorption of visible sunlight. The introduction of fused rings on the donor unit of AJ303 presented an appropriate energy level, less recombination and longer electron lifetime to achieve a power conversion efficiency (PCE) of 10.2%, far above that achieved for AJ301 of 6.2% with a [Co(bpy)(3)](2+/3+)-based electrolyte under standard AM1.5G solar irradiation (100 mW cm(-2)). The DSSCs based on AJ303 and AJ301 with [Cu(tmby)(2)](2+/+)-based electrolyte showed a lower PCE of 8.2% and 5.4%, respectively. Therefore, the results indicated that the introduction of a fused-ring in the donor group is a meaningful synthetic strategy to improve the photovoltaic performance.
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| 6. |
- Cai, Bin, et al.
(författare)
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Boosting the power conversion efficiency of perovskite solar cells to 17.7% with an indolo[3,2-b]carbazole dopant-free hole transporting material by improving its spatial configuration
- 2019
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 7:24, s. 14835-14841
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Tidskriftsartikel (refereegranskat)abstract
- The development of facilely synthesized, dopant-free hole-transporting materials (HTMs) with high efficiency is of great significance for the potential application of perovskite solar cells (PSCs). Herein, we report two novel indolo[3,2-b]carbazole (ICZ) based small molecules obtained via a three-step reaction in a high yield without using expensive catalysts, namely C201 and C202, and further apply them as dopant-free HTMs in PSCs. Compared with C201, C202 contains two additional biphenylamino groups to improve its spatial configuration. It is found that the interplay between the molecular geometry and the aggregation behavior can exert a great influence on the film formation property and thus on the device performance. Strikingly, the champion devices employing C202 as the HTM deliver a much higher PCE of up to 17.7%, which is substantially higher than that of devices containing C201 (8.7%) under 100 mW cm(-2) illumination (AM 1.5G). It is revealed that the C202 capping layer exhibits a more homogeneous and uniform surface morphology as compared to that of C201, which effectively reduces the charge recombination losses and facilitates charge extraction, leading to a much-enhanced photovoltaic performance. This is the first example of ICZ core-based small molecules as dopant-free HTMs in PSCs. Moreover, the PSCs containing C202 as the HTM also exhibited good long-term stability under ambient conditions (40% RH) as compared to devices with doped spiro-OMeTAD, due largely to the hydrophobic nature of C202 which prevented moisture from destroying the perovskite film. This work offers a new avenue for developing cost-effective and stable HTMs for PSCs and other optoelectronic devices.
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| 7. |
- Cai, Bin, et al.
(författare)
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High isotropic dispiro structure hole transporting materials for planar perovskite solar cells
- 2019
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Ingår i: Journal of Energy Challenges and Mechanics. - : Elsevier. - 2056-9386. ; 32, s. 152-158
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Tidskriftsartikel (refereegranskat)abstract
- Two novel fluorene-based hole transporting materials (HTMs) were synthesized to be used in perovskite solar cells (PSCs). C102 was designed based on C101 by simply linking the two carbon-carbon single bonds to compose a "dispiro" structure. Their typically similar structures cause them sharing almost the same energy levels. However, their photovoltaic performances are quite different due to the small variations. The PSC that contained the "dispiro" structure, C102, reached a power conversion efficiency (PCE) of 17.4%, while the device contained C101, obtained a lower PCE of 15.5%. Electrochemical properties and Photovoltaic characterization of the two materials have been investigated to explain the result. It is shown that C102 has a stronger ability to transport holes and resist the charge recombination. Thus, the dispiro structure should be more appropriate being used as HTM in PSCs. Physics, Chinese Academy of Sciences.
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| 8. |
- Cai, Bin, et al.
(författare)
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Unveiling the light soaking effects of the CsPbI3 perovskite solar cells
- 2020
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 472
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Tidskriftsartikel (refereegranskat)abstract
- Pure inorganic perovskite of CsPbI3 attracts great attentions due to its excellent thermal stability and more suitable bandgap for tandem solar cells. The power conversion efficiency (PCE) of CsPbI3 perovskite solar cells has swiftly increased to 19.03%. However, extensive researches on the material property and photovoltaic characterization are rather rare in the literatures. In this study, a remarkable light soaking effect is found in the CsPbI3 based perovskite solar cells as the PCE increases from 10.8% to 18.3% after 180 s soaking under AM 1.5G sunlight. Mechanisms behind this reproducible soaking effect have also been studied. It reveals that the depressed dark current caused by a stronger built-in field and the decreased defects density passivated by the photogenerated electrons result in the enhanced PCE after light soaking. Moreover, we carefully characterize that the supposed "HPbI3" should be "DMAPbI(3)" synthesized through anti-solvent vapor recrystallisation method.
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| 9. |
- Chen, Cheng, et al.
(författare)
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Degradation of Cyanoacrylic Acid-Based Organic Sensitizers in Dye-Sensitized Solar Cells
- 2013
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Ingår i: ChemSusChem. - : Wiley-VCH Verlagsgesellschaft. - 1864-5631 .- 1864-564X. ; 6:7, s. 1270-1275
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Tidskriftsartikel (refereegranskat)abstract
- Organic dyes have become widely used in dye-sensitized solar cells (DSSCs) because of their good performance, flexible structural modifications, and low costs. To increase the photostability of organic dye-based DSSCs, we conducted a full study on the degradation mechanism of cyanoacrylic acid-based organic sensitizers in DSSCs. The results showed that with the synergy between water and UV light, the sensitizer could desorb from the TiO2 surface and the cyanoacrylic acid unit of the sensitizer was transformed into the aldehyde group. It was also observed that the water content had a great effect on the degradation process. Our experiments conducted using O-18-labeled water demonstrated that the oxygen atom of the aldehyde group identified in the degraded dye came from the solvent water in the DSSCs. Therefore, controlling the water content during DSSC fabrication, good sealing of cells, and filtering the UV light are crucial to produce DSSCs that are more durable and robust.
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| 10. |
- Chen, Cheng, et al.
(författare)
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Efficient Panchromatic Organic Sensitizers with Dihydrothiazole Derivative as pi-Bridge for Dye-Sensitized Solar Cells
- 2013
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 5:21, s. 10960-10965
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Tidskriftsartikel (refereegranskat)abstract
- Novel organic dyes CC201 and CC202 with dihydrothiazole derivative as pi-bridge have been synthesizedand applied in the DSSCs. With the synergy electron-withdrawing of dihydrothiazole and cyanoacrylic acid, these two novel dyes CC201 and CC202 show excellent response in the region of 500-800 nm. An efficiency as high as 6.1% was obtained for the device fabricated by sensitizer CC202 together with cobalt electrolyte under standard light illumination (AM 1.5G, 100 mW cm(-2)). These two novel D-pi-A panchromatic organic dyes gave relatively high efficiencies except common reported squaraine dyes.
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