Trap center study in hybrid organic-inorganic perovskite using thermally stimulated current (TSC) analysis

Abstract

This paper presents results of a study that allowed identifying states of traps in thin films of hybrid organic-inorganic perovskite compounds based on methylammonium lead halide with different compositions CH3NH3PbX3 (X is Cl, Br or I) prepared by spin-coating, through Thermally Stimulated Current (TSC) measurements. Special emphasis was done in studying the influence of the composition and adsorption of oxygen on the depth of traps and on the density of states associated with trapping centers. Deconvolution of the TSC curves obtained from measurements made inside a vacuum chamber under different oxygen partial pressures, revealed the presence of traps centers whose activation energies are affected by the oxygen concentration. It was also found that TSC peaks do not appear in TSC measurements carried out at pressures less than 0.1 mbar, indicating that the possible nature of the identified traps centers is related to oxygen adsorbed superficially and/or located into the grain boundaries.

Methylammonium-chloride post-treatment on perovskite surface and its correlation to photovoltaic performance in the aspect of electronic traps

“…10 Nanostructural defects are supposed to originate from the susceptibility to chemical reactions as supported by the observed impacts of molecular species on the electronic traps of perovskite. 10,19 Considering that the electron donating groups (Lewis base) can result in the defect passivation, the chemical states of chlorine is worth understanding to enable the photovoltaic performance enhancement. 20 The chlorine-mediated reduction of both nonradiative recombination (Shockley-Read-Hall) and trapping/ detrapping of photocarriers validates the defect reduction.…”

Verringerung schädlicher Defekte für leistungsstarke Metallhalogenid‐Perowskit‐Solarzellen

“…Punkt (2) bezieht sich auf die Probenmessbedingungen (z. B. Physisorption und/oder Chemisorption von Gasen wie O 2 und H 2 O, Temperatur, Lichtintensität), die signifikante Auswirkungen auf die Charakterisierung von Defekten haben . So untersuchten Gordillo et al .…”

“…B. Physisorption und/oder Chemisorption von Gasen wie O 2 und H 2 O, Temperatur, Lichtintensität), die signifikante Auswirkungen auf die Charakterisierung von Defekten haben . So untersuchten Gordillo et al . beispielsweise mit der TSC‐Technik die Auswirkungen der Sauerstoffadsorption auf die Energieniveaus von Fallen und die Dichte von Fallenzentren.…”

Characterization of trap states in perovskite films by simultaneous fitting of steady-state and transient photoluminescence measurements

“…Table I lists the symbols used in the analytical solution, and the equations related to SRH recombination [Eqs. (5)- (7)] were derived by Shockley and Read.…”

“…Electrical characterization methods for measuring the trap density and energy level include thermally stimulated current and capacitance vs. frequency measurements at different temperatures. [7][8][9][10] However, both techniques require electrical contacts on the sample which can introduce additional recombination, while the application of an electrical bias can also induce ion migration. Temperature-dependent measurements also present challenges for perovskites due to the possibility of phase transitions and/or thermal degradation.…”