Abstract
The use of plasmonic nanoparticles (NPs) in dye-sensitized solar cells (DSSCs) in an effort to enhance their power conversion efficiencies (PCEs) increases light absorbance of the cells but also affect their electron dynamics. This has contributed to the failure of plasmonic NPs to make the expected high impact of PCE enhancement. Herein, we investigated the wide range effects of plasmonic NPs on the performance of DSSCs, using extended characterization and a systematic approach. We prepared DSSCs using Ag@TiO2 NPs-doped TiO2 photoanodes. Using a wide range doping concentration, we obtained panchromatic enhancement effect with two optimal doping concentrations (0.1 and 1 wt. %).They enhanced PCE via mainly: a) optimal band alignment for efficient charge injection; and b) a balance of the negative and positive effects of plasmonic NPs on cell performance parameters (open circuit voltage, fill factor, charge transfer resistance against recombination, electron life time and charge collection efficiency); respectively. The PCE of the pristine sample increased from 4.66 to 4.88 and 5.00% via these 2 routes, respectively. The major cause of not obtaining very high PCE was charge recombination from high charge density. Thus, these observations might serve as invaluable guidance for the preparation of highly efficient plasmonic DSSCs.
Highlights
Dye-sensitized solar cells (DSSCs) have evolved as credible alternative to conventional solid state p-n junction photovoltaics, with their core advantages of facile & low-cost fabrication, environmentally friendly, and good performance under lowlight conditions[1,2,3,4]
Two optimal doping concentrations were observed with enhanced PCE over a reference pristine cell of PCE of 4.66%: 1) 0.1%; with the highest Jsc, with the main enhancement via efficient charge injection, by lowering the fermi level of the TiO2 photoanode, producing a PCE of 4.88%; and 2) 1%; with the main enhancement via the electron-sink effect improving cell performance parameters of Jsc, Voc, fill factor (FF) and Rct, producing a PCE of 5.00%
With the appropriate modification to harvest the abundant charge carriers generated, this expected impact for highly efficient DSSCs can be achieved. To put it rather if a plasmonic DSSC is designed to harvest the high charge density of electrons induced by the plasmonic NPs, extremely high PCE can be achieved to meet the desired high expectation of plasmonic DSSCs
Summary
Dye-sensitized solar cells (DSSCs) have evolved as credible alternative to conventional solid state p-n junction photovoltaics, with their core advantages of facile & low-cost fabrication, environmentally friendly, and good performance under lowlight conditions[1,2,3,4]. Reported that plasmonic NPs in DSSCs have two effects: the plasmonic (light absorbance enhancement) and charging (electron dynamics) effects They used Au NPs with two different cappings: SiO2 (an insulator to prevent electron charging of the Au core) and TiO2 (a semiconductor that would allow transfer of electrons to charge the Au core). Observed the enhancement effect on light absorbance, and a resultant enhanced Jsc and PCE They observed the major plasmonic NPs enhancement effect on incident photon-to-current efficiency (IPCE) in the wavelength region of 400–500 nm, where the LSPR peak of their NPs is located. They were able to reduce photoanode thickness and still obtained a higher PCE. They observed decreased Jsc and PCE at higher (>0.6%) plasmonic doping conc., which they suggested was probably due to increased trapping of photogenerated electrons by Ag and conversion of part of the incident solar power into heat
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