In-situ thermal fabrication of photodetectors based on methylammonium lead bromide perovskite.

This paper presents low cost fabrication method of MAPbBr3 crystalline structures directly on the polylactic acid (PLA) carbon-coated substrates. Fabrication was carried out using three different crystallization processes: inverse temperature crystallization (ITC), anti-solvent vapor-assisted crystallization (AVC) and combination of both methods. This paper also includes the study of crystallization kinetics for both the perovskite and its precursors. Moreover, temperature modulated space-charge-limited current method (TM-SCLC) was applied to the measured current-voltage characteristics to estimate the concentration of free and trapped charge carriers, the microscopic mobility of free charge carriers, the thermodynamic position of the Fermi level as well as the position of localized states and their concentration. Based on the acquired data we determined following microscopic carrier mobilities and thermodynamic Fermi level positions: μ+/μ− ≈ 0.2/4.0 cm2/V/s, ΔEF ≈ –0.48 eV for PbBr2, μ+/μ− ≈ 10/10 cm2/V/s, ΔEF ≈ –0.575 eV for MABr, and μ+/μ− ≈ 10/300 cm2/V/s, ΔEF ≈ –0.57 eV for MAPbBr3). By comparing our model with literature data (bandgap width, permittivity, effective mass of carriers, etc.) we found and characterized the monoenergetic (bi-exponential) localized states near Fermi level of the studied materials (deep traps for PbBr2, shallow traps for MAPbBr3, and states at the Fermi level for MABr). [ABSTRACT FROM AUTHOR]