A study of trap and recombination centers in MAPbI₃ perovskites

Abstract

Trapping and recombination processes in thin films of CHNHPbI (MAPbI) were studied by means of transient photoconductivity measurements and theoretical simulations of the relaxation curves resulting from the photocurrent measurements; in particular, the influence of temperature as well as of the sample temperature and intensity of illumination and pressure inside the measurement system on the photoconductivity response, were studied. The experimental curves of photocurrent were analyzed using the real part of the Fourier transform. The study revealed that the photocurrent of the MAPbI films, measured at atmospheric pressure, is mainly governed by surface related processes induced by chemisorption and desorption of oxygen, whereas the photocurrent resulting from measurements performed in a vacuum is mainly governed by bulk related processes. It was found that, in general, the photocurrent response is affected by both trap assisted fast recombination processes and traps whose activation process is delayed, with the contribution in the intensity of the photocurrent of the first process being greater that of the second one. Evidence that the MAPbI film exhibits a deep trap state at around 459 meV attributed to trap assisted recombination was found; furthermore, the MAPbI films present shallow trap states at 129 and 24 meV that correspond to trap states whose activation process is delayed.

Unravelling the effects of oxidation state of interstitial iodine and oxygen passivation on charge trapping and recombination in CH3NH3PbI3 perovskite: a time-domain ab initio study

“…17 However, the PCEs are still lower than the Shockley-Queisser limit 18 for a single p-n junction solar cell due to the presence of channels for nonradiative charge and energy losses caused by various intrinsic and extrinsic defects. [19][20][21] Intrinsic defects are inevitable in low-temperature solutionprocessed LHPs due to the low stability against thermal and light radiation. 22 Dozens of experimental and theoretical works have explored the roles played by a large number of native point defects in LHPs, 20,[23][24][25][26][27][28][29][30] which found those defects have signicant impact on the performance of perovskite solar cells by controlling the quality of lms and carrier dynamics.…”

Polarization‐Dependent Photoluminescence of a Highly (100)‐Oriented Perovskite Film

“…[5][6][7] As a result, the power-conversion efficiency (PCE) of the perovskite solar cells (PSC) has reached 25.2 %. [9,10] However, owing to a lack of deep-understanding of fabrication methods and the underlying mechanisms, a majority of perovskite thin films being reported are [001]-or randomly oriented ones, [11,12,22] leaving the perovskites oriented in [100] direction relatively less understood. [9,10] However, owing to a lack of deep-understanding of fabrication methods and the underlying mechanisms, a majority of perovskite thin films being reported are [001]-or randomly oriented ones, [11,12,22] leaving the perovskites oriented in [100] direction relatively less understood.…”

“…[8] In this regard, numerous studies have been carried out to investigate the optoelectronic properties and the trap state dynamics of methylammonium lead iodide (MAPbI 3 , MA = CH 3 NH 3 ) perovskite in the form of either a thin film or a single crystal. [9,10] However, owing to a lack of deep-understanding of fabrication methods and the underlying mechanisms, a majority of perovskite thin films being reported are [001]-or randomly oriented ones, [11,12,22] leaving the perovskites oriented in [100] direction relatively less understood. Recently, Cho et al fabricated a MAPbI 3 film in [100] direction by using the temperature-gradient-assisted crystallization method to investigate the optical and electrical properties of the film.…”

Reversible air-induced optical and electrical modulation of methylammonium lead bromide (MAPbBr3) single crystals

“…This can be regarded as an increase of charge carrier numbers in MSC. 46 After the initial stage, the chamber is refilled with air, accompanied by a quick decrease in the dark current. When the chamber is evacuated, the dark current of the MSC increases immediately.…”