Effect of high energy proton irradiation on MAPbI 3 films for space applications observed by micro-Raman spectroscopy

HERRERA MARTÍNEZ, WALTER O.; IBARRA, M. LUJÁN; GIUDICI, PAULA; PEREZ, M. DOLORES; CORREA GUERRERO, NATALIA B.; HERRERA MARTÍNEZ, WALTER O.; IBARRA, M. LUJÁN; GIUDICI, PAULA; PEREZ, M. DOLORES; CORREA GUERRERO, NATALIA B.

Materials Advances

Royal society of Chemistry

Año: 2020 vol. 1 p. 2068 - 2073

Irradiation of samples with 10 MeV protons is a standardtest for simulation of the outer space environmentin order to qualify devices and materials for space applications. Micro-Raman spectroscopy allows one todetermine the irradiation effect on methylammonium lead iodide (MAPbI3) thin films under ambientconditions and encapsulated. For the unprotected films, the vibrational modes matched previously reportedlead oxide phonon frequencies and the appearance of superficial oxides was confirmed by EDAXS analysis.However, the Raman shifts corresponding to PbO were not observed for the irradiated encapsulatedsamples, indicating that oxidation occurs after surface exposure to ambient oxygen. Similar effects havebeen observed by photooxidation where the highly reactive superoxide radical is involvedintheoxidationmechanism. We propose that irradiation promotes excitation of the electron cloud, which readily reducesthe surface adsorbed oxygen, and thislater bonds to the accessible Pb atoms.