CsPbBr3 deposited by laser ablation: effects of post-growth aging, oxygen adsorption and annealing on film properties

Abstract

All-inorganic perovskites are widely investigated as a new generation of materials thanks to their superior optoelectronic properties and better stability than hybrid organic–inorganic perovskites. In particular, cesium lead bromide (CsPbBr3) exhibits advantageous properties for numerous applicative fields (photovoltaics, light-emitting diodes, photodetectors, lasing, field effect transistors, and ionizing radiation detectors). The performance of CsPbBr3 being critically dependent on the deposition technique, proper understanding and optimization of the fabrication process are demanding. Despite the well-known potentiality of the Pulsed Laser Deposition (PLD) technique in depositing films with complex stoichiometry, a very limited number of literature studies report on the successful deposition of CsPbBr3 films by PLD. Recently, the authors disclosed the impact of the uneven masses of Cs, Pb, and Br on the film stoichiometry and guidelines to recover the desired composition. Herein, we exploit stoichiometric mechano-chemically synthesized targets to deposit, by nanosecond-PLD (λ = 248 nm, τ = 20 ns, room temperature, fluence of 1 J/cm2), CsPbBr3 films to be studied following time aging, thermal heating and exposure to high relative humidity. Even in the presence of the characteristic absorption peak at ~ 520 nm, the freshly deposited film shows no photoluminescence. Photoluminescence is switched on by thermal annealing (at 250 and 350 °C) or after a few days (at least 15) of exposure to air and it persists over time. Films present interesting morphology evolution and oxygen adsorption following heating.