Propriedades fotofísicas de filmes multicamadas de perovskita livre de chumbo e compostos eletroluminescentes

Abstract

Luminescent organic compounds play an essential role in the fabrication of photosensitive active layers, spanning a variety of applications from sensors to lightemitting diodes, photovoltaic systems, among others. In this context, we explored the creation of multilayer films from a hybrid Perovskite (P), with the configuration CH3NH3SnIxCl3-X, combined with recognized electroluminescent compounds such as Rubrene (R), and the polymer Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], MEH-PPV (M), which were deposited by the Layer-by-Layer and spin-coating techniques, and their photophysical properties were studied. Using steady-state and time-resolved fluorescence spectroscopy, it was possible to evaluate the optimal conditions for the production of thin films of the isolated compounds and combinations of interest (bi- and trilayers - P/M; P/R; P/M/R and P/R/M), as well as their photophysical properties. Steady-state electronic spectra demonstrated higher efficiency for films prepared from the deposition of layers of perovskite, Rubrene, and MEH-PPV, using solutions with concentrations of 0.6 – 10-5 and 10-8 mol.L-1, respectively. The layer-by-layer technique involved a 90-second immersion, and spincoating films required 100, 40, and 60 seconds of spin-up rotation for perovskite, Rubrene, and MEH-PPV, respectively. Single point and lifetime mapping analyses, using pulsed lasers (373, 452, and 507 nm), indicated tri-exponential behavior in all evaluations. The results showed for P/R layer-by-layer and spin-coating bilayers excited states with greater sensitivity to the excitation wavelength, prolonging lifetimes with decreasing irradiation length. Mapping analysis indicated regions with higher Eficiência de FRET for P/R when excited at 373 and 452 nm, and for P/M at 507 nm excitation. The Single point data of the Trilayers showed that the inversion in the order of deposition of the semiconductors directly influenced the formation of the system's excited states, with the P/M/R film showing greater sensitivity to the photophysical processes as the excitation length varied. and P/R/M greater stability. Mapping indicated higher FRET rates for P/M/R produced by layer-by-layer, which was selected for UV-Vis sensing studies