Postdoc, University of Mississippi
Newly developed method allows to achieve photo-voltage by DSCs which was not possible before
Global energy demand is steady increasing. Sustainable fossil fuel-free pathways to electricity and fuel production such as conversion of water to H2 and CO2 to carbons fuels with only O2 as a by-product are highly desirable. Solar energy is the most abundant energy source, however; energy conversion and storage needs to increase in efficiency for practical applications. Dye-sensitized solar cells (DSCs) are promising in terms of cost, stability, commercial viability and environmental impact when compared with many solar cell technologies. Additionally, DSCs are an exceptionally attractive solar cell technology for converting high potential energy photons efficiently with the highest single DSC cell giving a Voc value of 1.4 V. Traditionally, research efforts for DSCs have targeted achieving high efficiency single-junction devices by balancing photocurrent and Voc. However, single cell devices convert all absorbed photons regardless of potential energy to the same voltage resulting in significant energetic waste from high-energy solar spectrum photons. Series tandem DSCs (ST-DSCs) combined with low energy photon utilizing solar cells such as GaAs or silicon offer device architectures to circumvent this potential energy loss. We developed a unique methodology to achieve high enough photo-voltage by single illuminated area DSCs which has the potential to power electrocatalysts for producing H2 fuel from water, CO from CO2 and consumer electronics such as smartphones and Li-Ion batteries which require approx.3.7-4.0 V to charge.
Abstract: High photovoltage dye-sensitized solar cells (DSCs) offer an exceptional opportunity to power electrocatalysts for the production of hydrogen from water and the reduction of CO2 to usable fuels with a relatively cost-effective, low-toxicity solar cell. Competitive recombination pathways such as electron transfer from TiO2 films to the redox shuttle or oxidized dye must be minimized to achieve the maximum possible photovoltage (Voc) from DSC devices. A high Voc of 882 mV was achieved with the iodide/triiodide redox shuttle and a ruthenium NCS-ligated dye, HD-2-mono, by utilizing a combined approach of: (1) modulating the TiO2 surface area through film thickness and nanoparticle size selection, (2) addition of a MgO insulating layer, and (3) capping available TiO2 film surface sites post film sensitization with an F-SAM (fluorinated self- 1 assembled monolayer) treatment. The exceptional Voc of 882 mV observed is the highest achieved for the popular NCS containing ruthenium sensitizers with >5% PCE and compares favorably to the 769 mV value observed under common device preparation conditions.
Pub.: 28 Dec '16, Pinned: 28 Jun '17
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