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Silicon nanocrystal hybrid photovoltaic devices for indoor light energy harvesting
摘要： Silicon nanocrystals (SiNCs) featuring size-dependent novel optical and electrical properties have been widely employed for various functional devices. We have demonstrated SiNC-based hybrid photovoltaics (SiNC-HPVs) and proposed several approaches for performance promotion. Recently, owing to the superiorities such as low power operation, high portability, and designability, organic photovoltaics (OPVs) have been extensively studied for their potential indoor applications as power sources. SiNCs exhibit strong light absorption below 450 nm, which is capable of sufficient photocurrent generation under UV irradiation. Therefore, SiNC-HPVs are expected to be preferably used for energy harvesting systems in indoor applications because an indoor light source consists of a shorter wavelength component below 500 nm than solar light. We successfully demonstrated SiNC-HPVs with a PCE as high as 9.7%, corresponding to the output power density of 34.0 mW cm?2 under standard indoor light irradiation (1000 lx). In addition, we have found that SiNC defects working as electron traps influence the electrical properties of SiNCs substantially, a thermal annealing process was conducted towards the suppression of defects and the improvement of the SiNC-HPVs performance.
关键词： Silicon nanocrystals,Power conversion efficiency,Indoor light energy harvesting,Thermal annealing,Hybrid photovoltaics
更新于2025-09-23 15:21:01
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Highly efficient indoor light quasi-solid-state dye sensitized solar cells using cobalt polyethylene oxide-based printable electrolytes
摘要： High-performance printable electrolytes (PEs) containing Co+2/Co+3 or I-/I3- redox-couple are prepared to fabricate quasi-solid-state (QS) dye-sensitized solar cells (QS-DSSCs) for room light environment applications. Polyethylene oxide (PEO) and poly(methyl methacrylate) (PMMA) are utilized to prepare PEs. Various parameters are regulated to obtain the optimal power conversion efficiencies (PCEs). For the I-/I3- system, the QS-DSSCs using PEO and PEO/PMMA PEs achieve nearly identical PCEs (16.32% and 16.40%, respectively) under the optimal conditions. However, the PCEs obtained for the Co+2/Co+3 system are markedly higher and the cell using PEO PE has a higher PCE (21.06%) than that using PEO/PMMA (18.14%). This difference is ascribed to the different composition of Li+ and Co+3 around the photoelectrode. The presence of Li+ around the interface will repel Co+3 away from the interface, decreasing the recombination of excited electrons to Co+3. According to the molecular structure, PMMA has more lone pair electrons to coordinate with Li+ ions, which will decrease the concentration of free Li+ more significantly than does by PEO. Therefore, the presence of PMMA will decrease and increase, respectively, the Li+ and Co+3 concentrations at the photoelectrode/electrolyte interface, resulting in more significant recombination of electrons to the Co+3. Consequently, the PCE of the PEO/PMMA cell is lower than that of the PEO cell. This effect doesn’t occur in I-/I3- system because the concentration variation of negatively charged ions did not affect significantly the electrons recombination at the interfacial. By using this cobalt PE, a bifacial QS-DSSC can achieve PCEs of 17.22% and 14.25%, respectively, under front-side and back-side illumination by 200 lux T5 light. A sub-module QS-DSSC using the cobalt PE can attain a PCE of 12.56%.
关键词： indoor light,sub-module cells,poly ethylene oxide,bi-facial cell,cobalt electrolyte,printable electrolyte
更新于2025-09-23 15:21:01
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Understanding the Performance of Organic Photovoltaics under Indoor and Outdoor Conditions: Effects of Chlorination of Donor Polymers
摘要： Understanding the effects of the chemical structures of donor polymers on the photovoltaic properties of their corresponding organic photovoltaic (OPV) devices under various light-intensity conditions is important for improving the performance of these devices. We synthesized a series of copolymers based on poly[(2,6-(4,8-bis(5-(2-thioethylhexyl)thiophen-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-TS) and studied the effects of chlorine substitution of its thiophene-substituted benzodithiophene (BDT-Th) unit on its photovoltaic properties. The chlorination of the polymer resulted in a bulk heterojunction (BHJ) morphology optimized for efficient charge transport with suppressed leakage current and an increased open-circuit voltage of the OPV device; this optimization led to a remarkable enhancement of the OPV device’s power conversion efficiency (PCE) not only under the condition of 1 sun illumination but also under the condition of low light intensity mimicking indoor light; the PCE increased from 8.7% for PBDB-TS to ~13% for the chlorinated polymers, PBDT-TS-3Cl and PBDT-TS-4Cl, under the 1 sun illumination condition and from 5.3% for PBDB-TS to 21.7% for PBDB-TS-4Cl under 500 lx fluorescence illuminance. Interestingly, although the OPV PCEs under 1 sun illumination were independent of the position of chlorine substitution onto the polymer, the PBDB-TS-4Cl exhibited better performance under simulated indoor light than its derivative PBDB-TS-3Cl. Our results demonstrate that efficient light absorption and charge-carrier generation play key roles in achieving high OPV efficiency under low-light-intensity conditions.
关键词： bulk heterojunction,benzodithiophene,indoor light,chlorine substitution,organic photovoltaic
更新于2025-09-23 15:19:57
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High performance and stable nonfullerene acceptor-based organic solar cells for indoor to outdoor light
摘要： We synthesized a donor polymer of bis(2-ethylhexyl)thiophene-substituted benzodithiophene (BDT-Th) and 1,3-bis(2-ethylhexyl)-5,7-di(thiophene-2-yl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione, for which the BDT-Th unit includes chlorine and sulfur-bridged 2-ethylhexyl in the thiophene side group. When compared with PBDB-TF, which includes fluorine and 2-ethylhexyl in BDT-Th, PBDB-TSCl shows more efficient exciton dissociation and charge-generation, which is probably because large dipole moment changes from ground to excited states lead to reduced exciton binding energy. Consequently, despite small donor-acceptor interface in the bulk-heterojunction (BHJ) film, PBDB-TSCl achieves higher photovoltaic performance than PBDB-TF under various light intensities; PBDB-TSCl achieved higher efficiency of 13.13% than 12.12% of PBDB-TF under 1 sun illumination. Moreover, PBDB-TSCl showed the highest efficiency of 21.53% with fill factor (FF) of 76.29% under a 500 lux fluorescence lamp, whereas PBDB-TF has lower efficiency of 15.57% with FF of 65.25%. Furthermore, the PBDB-TSCl device shows improved thermal stability due to more stabilized morphology of its BHJ film.
关键词： indoor light,nonfullerene acceptor,outdoor light,organic solar cells,thermal stability,photovoltaic performance
更新于2025-09-19 17:13:59
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High-efficiency Bifacial Dye-Sensitized Solar Cells for application under Indoor Light Conditions
摘要： High-efficiency, stable bifacial dye-sensitized solar cells (DSSCs) are prepared for application under indoor light conditions. A 3-methoxypropionitrile solvent and cobalt redox couples are utilized to prepare the electrolytes. To obtain the best cell performance, the components of the DSSCs, including electrolytes, photoanodes, and counter electrodes (CEs), are regulated. The experimental results indicate that an electrolyte comprising a Co (II/III) ratio of 0.11/0.025 M, 1.2 M 4-tert-butylpyridine, Y123 dye, a CE with the platinum (Pt) layer thickness of 0.16 nm, a photoanode with titanium dioxide (TiO2) layer thickness of 10 μm (6 μm main layer and 4 μm scattering layer) are the best conditions under which to achieve a high power conversion efficiency. It is also found that the best cells have high recombination resistance at the photoelectrode/electrolyte interface and low charge transfer resistance at the counter electrode/electrolyte interface, which contributes, respectively, the high current density and open-circuit voltage of the corresponding cells. This DSSC can achieve efficiencies of 22.66%, 23.48%, and 24.52%, respectively, under T5 light illumination of 201.8, 607.8 and 999.6 lux. For fabrication of bifacial DSSCs with semi-transparent property, photoanodes without TiO2 scattering layer, as well as an ultra-thin Pt film are utilized. The thicknesses of the TiO2 main layer and Pt film are re-regulated. It shows that a Pt film with 0.55 nm thickness has both high transmittance (76.01%) and catalytic activity. By using an 8 μm TiO2 main layer, optimal cell efficiencies of 20.65% and 17.31% can be achieved, respectively, for the front-side and back-side illuminations of 200 lux T5 light. The cells are highly stable during a long-term performance test at both 35 oC and 50 oC.
关键词： indoor light,liquid electrolyte,cobalt redox couple,thin Pt layer,bifacial DSSCs
更新于2025-09-19 17:13:59
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Spiro[fluorene-9,9a?2-phenanthren]-10a?2-one as auxiliary acceptor of D-A-??-A dyes for dye-sensitized solar cells under one sun and indoor light
摘要： Six novel organic dyes (RY1~RY6) containing spiro[fluorene-9,9'-phenanthren]-10'-one as an auxiliary acceptor were synthesised and effectively used for the fabrication of D-A-π-A type dye-sensitized solar cells (DSSCs). The molecular structures were modified by introducing a novel spiro[fluorene-9,9'-phenanthren]-10'-one auxiliary acceptor group between the donor and the π-bridge. The molecular rigidity can be enhanced by depressing intermolecular aggregation and carbonyl group can trapping the Li+ ions to retard the charge recombination. The sensitizer RY3 was found to perform remarkable light-harvesting efficiency of 6.30% at AM1.5 solar condition and 21.67% at TL84 (2500 lux) illuminations without DCA co-deposition. For further improvement, a higher efficiency can be achieved through a suitable co-sensitization of N719 and RY3, which displayed an efficiency of 8.55% under one sun (AM 1.5). While operated under indoor light, the efficiency was boosted to 25.57% and 27.04% at 1000 & 2500 lux illuminations, respectively. The high performance of co-sensitization of N719 and RY3 can be ascribed to a high surface coverage and a broader range of absorption wavelength. Stability test of the device co-sensitized with N719 and RY3 showed a mild decay of PCE 3.74% after 96 h, while it retained 84.49% of its original PCE after 336 h in ambient atmosphere without encapsulation.
关键词： Spiro[fluorene-9,9'-phenanthren]-10'-one,Co-sensitization,High performance under indoor light,Dyes sensitized solar cells
更新于2025-09-19 17:13:59