Synthesis and characterisation of methylammonium lead tri-bromide perovskites thin films by sequential physical vapor deposition

Methylammonium lead tri-bromide (MAPbBr(3)) thin films were grown by sequential physical vapor deposition of lead(II)bromide and methylammonium bromide (MABr). X-ray diffractograms confirmed the cubic MAPbBr(3) structure with Pm (3) over barm space group. UV-Vis spectra revealed a red shift in absorption onset from 540 to 550 nm as the thickness of MABr increased with an optimum band gap of 2.28 eV, obtain from a Tauc Plot. Field emission scanning electron micrographs showed large pin-hole-free and densely packed grains with average grain size that increased from 217 to 302 nm with the thickness of MABr. Analysis of dark current-voltage characteristics of Au/MAPbBr(3)/FTO devices revealed ohmic behaviour at low voltages and trap-limited space charge limited current at high voltages. The carrier mobility increased from 1.89 x 10(-2) to 1.08 x 10(-1) cm(2) V-1 s(-1) while trap density decreased from 1.89 x 10(16) to 1.40 x 10(16) cm(-3) as the thickness of MABr increased.