8 research outputs found
Identifying structure-absorption relationships and predicting absorption strength of non-fullerene acceptors for organic photovoltaics
Non-fullerene acceptors (NFAs) are excellent light harvesters, yet the origin of their high optical extinction is not well understood. In this work, we investigate the absorption strength of NFAs by building a database of time-dependent density functional theory (TDDFT) calculations of ∼500 π-conjugated molecules. The calculations are first validated by comparison with experimental measurements in solution and solid state using common fullerene and non-fullerene acceptors. We find that the molar extinction coefficient (εd,max) shows reasonable agreement between calculation in vacuum and experiment for molecules in solution, highlighting the effectiveness of TDDFT for predicting optical properties of organic π-conjugated molecules. We then perform a statistical analysis based on molecular descriptors to identify which features are important in defining the absorption strength. This allows us to identify structural features that are correlated with high absorption strength in NFAs and could be used to guide molecular design: highly absorbing NFAs should possess a planar, linear, and fully conjugated molecular backbone with highly polarisable heteroatoms. We then exploit a random decision forest algorithm to draw predictions for εd,max using a computational framework based on extended tight-binding Hamiltonians, which shows reasonable predicting accuracy with lower computational cost than TDDFT. This work provides a general understanding of the relationship between molecular structure and absorption strength in π-conjugated organic molecules, including NFAs, while introducing predictive machine-learning models of low computational cost
Polymer morphology and interfacial charge transfer dominate over energy-dependent scattering in organic-inorganic thermoelectrics
Rapid and high-resolution patterning of microstructure and composition in organic semiconductors using ‘molecular gates’
The Relation Between Social Embeddedness and Loneliness among Older Lesbian, Gay, and Bisexual Adults in the Netherlands
Interplay between Fullerene Surface Coverage and Contact Selectivity of Cathode Interfaces in Organic Solar Cells
The meniscus-guided deposition of semiconducting polymers
A primary advantage of polymer semiconductors compared to silicon-based semiconductors lies in its capability of being solution-processed for the large-scale fabrication of electronics that can be flexible, stretchable, implantable, biodegradable, and self-healing. Here, Gu and Shaw et al. review recent developments in meniscus-guided coating that can control thin-film morphology