Tweaking the Optoelectronic Properties of S‐Doped Polycyclic Aromatic Hydrocarbons by Chemical Oxidation

• Published in: Chemistry : a European journal Vol. 29; no. 11; pp. e202203115 - n/a
• Main Authors: Matuszewska, Oliwia, Battisti, Tommaso, Ferreira, Ruben R., Biot, Nicolas, Demitri, Nicola, Mézière, Cécile, Allain, Magali, Sallé, Marc, Mañas‐Valero, Samuel, Coronado, Eugenio, Fresta, Elisa, Costa, Rubén D., Bonifazi, Davide
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 21.02.2023; Wiley Subscription Services, Inc
• Subjects: Chemistry; Chemistry, Multidisciplinary; Congeners; Crystals; Electrochemical cells; Electrochemistry; Hydrogen peroxide; mixed-valence complexes; Optoelectronics; organic semiconductors; Oxidation; Physical Sciences; Polycyclic aromatic hydrocarbons; PXX; Room temperature; S-doping; Science & Technology; Single crystals; Sulfoxides; thin-film lighting; Valence; thin-film lighting; organic semiconductors; PXX; TRANSISTORS; EMITTING ELECTROCHEMICAL-CELLS; O-ANNULATION; S-doping; CHEMISTRY; mixed-valence complexes; polycyclic aromatic hydrocarbons; CYCLIZATION
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202203115

Peri‐thiaxanthenothiaxanthene, an S‐doped analog of peri‐xanthenoxanthene, is used as a polycyclic aromatic hydrocarbon (PAH) scaffold to tune the molecular semiconductor properties by editing the oxidation state of the S‐atoms. Chemical oxidation of peri‐thiaxanthenothiaxanthene with H2O2 led to the relevant sulfoxide and sulfone congeners, whereas electrooxidation gave access to sulfonium‐type derivatives forming crystalline mixed valence (MV) complexes. These complexes depicted peculiar molecular and solid‐state arrangements with face‐to‐face π–π stacking organization. Photophysical studies showed a widening of the optical bandgap upon progressive oxidation of the S‐atoms, with the bis‐sulfone derivative displaying the largest value (E00=2.99 eV). While peri‐thiaxanthenothiaxanthene showed reversible oxidation properties, the sulfoxide and sulfone derivatives mainly showed reductive events, corroborating their n‐type properties. Electric measurements of single crystals of the MV complexes exhibited a semiconducting behavior with a remarkably high conductivity at room temperature (10−1–10−2 S cm−1 and 10−2–10−3 S cm−1 for the O and S derivatives, respectively), one of the highest reported so far. Finally, the electroluminescence properties of the complexes were tested in light‐emitting electrochemical cells (LECs), obtaining the first S‐doped mid‐emitting PAH‐based LECs. Peri‐thiaxanthenothiaxanthene is used as a functional scaffold to engineer a molecular semiconductor, the properties of which can be tailored by editing the oxidation state of the S‐atoms. Oxidation with H2O2 led to the relevant sulfoxide and sulfone congeners, whereas electrooxidation yields sulfonium‐type derivatives forming crystalline mixed valence complexes.