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We report here the synthesis of undoped and Cu-doped Cs2ZnCl4 nanocrystals (NCs) in which we could tune the concentration of Cu from 0.7 to 7.5%. Cs2ZnCl4 has a wide band gap (4.8 eV), and its crystal structure is composed of isolated ZnCl4 tetrahedra surrounded by Cs+ cations. According to our electron paramagnetic resonance analysis, in 0.7 and 2.1% Cu-doped NCs the Cu ions were present in the +1 oxidation state only, while in NCs at higher Cu concentrations we could detect Cu(II) ions (isovalently substituting the Zn(II) ions). The undoped Cs2ZnCl4 NCs were non emissive, while the Cu-doped samples had a bright intragap photoluminescence (PL) at ∼2.6 eV mediated by band-edge absorption. Interestingly, the PL quantum yield was maximum (∼55%) for the samples with a low Cu concentration ([Cu] ≤ 2.1%), and it systematically decreased when further increasing the concentration of Cu …
American Chemical Society
Publication date: 
5 Jun 2020

Dongxu Zhu, Matteo L Zaffalon, Valerio Pinchetti, Rosaria Brescia, Fabrizio Moro, Mauro Fasoli, Marco Fanciulli, Aiwei Tang, Ivan Infante, Luca De Trizio, Sergio Brovelli, Liberato Manna

Biblio References: 
Volume: 32 Issue: 13 Pages: 5897-5903
Chemistry of Materials