Data mining with molecular design rules identifies new class of dyes for dye-sensitised solar cells

ACS Appl. Mater. Interfaces

Evans

2015

Self Cite

The dye…TiO 2 interfacial structure in working electrodes of dye-sensitized solar cells (DSCs) is known to influence its photovoltaic device performance. Despite this, direct and quantitative reports of such structure remain sparse. This case study presents the application of X-ray reflectometry to determine the preferred structural orientation and molecular packing of the organic dye, coumarin 343, adsorbed onto amorphous TiO 2. Results show that the dye molecules are, on average, tilted by 61.1° relative to the TiO 2 surface, and are separated from each other by 8.2 Å. These findings emulate the molecular packing arrangement of a monolayer of coumarin 343 within its crystal structure. This suggests that the dye adsorbs onto TiO 2 in one of its lowest energy configurations, i.e. dye…TiO 2 self assembly is driven more by thermodynamic rather than kinetic means. Complementary DSC device tests illustrate that this interfacial structure compromises photovoltaic performance, unless a suitably sized co-adsorbant is interdispersed between the coumarin 343 chromophores on the TiO 2 surface.

mentioning

confidence: 99%

Preferred Molecular Orientation of Coumarin 343 on TiO₂ Surfaces: Application to Dye-Sensitized Solar Cells

McCree-Grey

ACS Appl. Mater. Interfaces

Evans

2015

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“…This case study on a single family of dyes presents a "bottom-up" strategy to systematic materials discovery which complements recent efforts on "top-down" strategies associated with large-scale data-mining of new DSC dyes. [ 44 ] The use of molecular engineering to computationally design new dyes, in a systematic fashion, helps to shortlist the best dye candidates to take forward into an experimental materials discovery program. Given the much more time-and resource-intensive nature of such programs, this identifi cation and streamlining approach to materials discovery has the potential to afford a faster product return on research investment, vis a vis the workfl ow from research-to-innovation.…”

Section: Resultsmentioning

confidence: 99%

“…While the study was limited to known dye families, it could benefi t from the complementary materials discovery efforts that seek new families of dyes that explore more of chemical space. [ 44 ] Moving beyond current limits, it would be more optimal to parameterize dye excitation and redox processes within the context of their direct impact on the other material components of the DSC cell, i.e., compute the full ecology of the DSC cell during its operation. While such a multicomponent energy analysis which produces results with any confi dence has yet to be realized, studies are able to model dye···TiO 2 interfacial charge transfer using density functional theory.…”

Section: Further Developments For the Molecular Engineering Of Dsc Dyesmentioning

confidence: 99%

Transforming Benzophenoxazine Laser Dyes into Chromophores for Dye‐Sensitized Solar Cells: A Molecular Engineering Approach

Schröder

Advanced Energy Materials

Waddell

et al. 2015

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next-generation environmental technologies for advanced harvesting of solar energy. The operating principles of DSCs are well documented: a photoanode (working electrode) is covered in mesoporous and nanocrystalline metal oxide (usually TiO 2 ), which is sensitized by a monolayer of dye molecules adsorbed via anchoring groups. [ 2 ] Upon photon absorption, the excited dyes inject an electron into the conduction band of the semiconducting TiO 2 , generating a potential difference with respect to this working electrode and a counter-electrode (a transparent conducting oxide, usually fl uorine-doped tin oxide FTO). Thus, the adsorbed electron is transported to the counter-electrode, i.e., initiating the electrical current in the solar cell. An electrolyte solution between these electrodes acts as a redox couple, taking the electron from the counter-electrode and passing it back to the dye in order to regenerate its ground state, thus completing the electrical circuit. The redox process is catalyzed by platinum, a thin fi lm of which is coated into the counter-electrode. Due to its slow recombination with electrons from TiO 2 , the redox couple typically employed is I − / I 3 − . However, it is worth noting that a Co (II/III) tris(bipyridyl) redox couple is gaining traction as an alternative, given that it has a higher redox potential ( E redox ≈ +0.535 V) compared to I − / I 3 − ( E redox ≈ +0.35 V) and it mitigates better against energy losses in the dye regeneration process. [ 1,3,4 ] As the most effi cient, and hence most commonly used dyes contain the expensive and relatively rare transition metal ruthenium, [ 5,6 ] metal-free organic dyes have become attractive candidates due to their low cost, high molar extinction coeffi cients, and inherent design fl exibility. [ 5,6 ] Most organic dyes are based on donor-(π-bridge)-acceptor ( D -π-A ) architectures, in which a π-conjugated system connects an electron-donating group ( D ) with an electron-accepting group ( A ). Upon photoexcitation, the resulting "push-pull" effect is characterized by anisotropic intramolecular charge transfer (ICT) from the donor to the acceptor, which facilitates electron injection into the semiconductor. Modifi cations to the three main components of the D -π-A architecture allow a fi ne-tuning of the magnitude of this "push-pull" effect, in terms of the molar extinction coeffi cient (ε), the maximum peak absorption wavelength (λ max peak ), tris(bipyridyl) suggests promise for these computationally designed dyes as co-sensitizers for DSC applications.

“…While our current models enable us to predict phase-transition temperatures for known compounds, our ultimate goal is to predict and experimentally validate new classes of compounds for magnetic and superconducting applications. While data-driven materials discovery has been achieved in other fields of research 10,40,41 , it remains a distant goal in the magnetic and superconductivity domain. Yet, our toolkit is poised for this endeavour since its databank utility could be reverse engineered with some toolkit adaptations to predict material compositions that have desired phase transitions.…”

Section: Discussionmentioning

confidence: 99%

Magnetic and superconducting phase diagrams and transition temperatures predicted using text mining and machine learning

Court

2020

npj Comput Mater

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Predicting the properties of materials prior to their synthesis is of great importance in materials science. Magnetic and superconducting materials exhibit a number of unique properties that make them useful in a wide variety of applications, including solid oxide fuel cells, solid-state refrigerants, photon detectors and metrology devices. In all these applications, phase transitions play an important role in determining the feasibility of the materials in question. Here, we present a pipeline for fully integrating data extracted from the scientific literature into machine-learning tools for property prediction and materials discovery. Using advanced natural language processing (NLP) and machine-learning techniques, we successfully reconstruct the phase diagrams of well-known magnetic and superconducting compounds, and demonstrate that it is possible to predict the phase-transition temperatures of compounds not present in the database. We provide the tool as an online open-source platform, forming the basis for further research into magnetic and superconducting materials discovery for potential device applications.npj Computational Materials (2020) 6:18 ; https://doi.