Determination of Defect Levels in Melt-Grown All-Inorganic Perovskite CsPbBr<sub>3</sub> Crystals by Thermally Stimulated Current Spectra

Zhang, Mingzhi; Zheng, Zhiping; Fu, Qiuyun; Guo, Peng; Zhang, Sen; Chen, Cheng; Chen, Hualin; Wang, Mei; Luo, Wei; Tian, Yuhui

doi:10.1021/acs.jpcc.8b01532

Cited by 50 publications

(50 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Total trap concentrations are of the order of 10 18 cm −3 . Such high defect concentrations have been already observed in lead halide perovskite solar cell structures [8] and similar samples [6]. Trap occupancy of the shallowest defect is either small or negligible: being peaked at 340 K, close to room temperature, it fades away very quickly, so in B and C measurements the long decay time adopted is sufficient to make it disappear.…”

Section: Thermally Stimulated Currentsmentioning

confidence: 55%

“…Only very few works on thermally stimulated currents applied to CsPbBr 3 are available up to now in the literature. A study on single crystal CsPbBr 3 [8] analyzed TSC spectra using SIMultaneous-Peak Analysis (SIMPA) in the assumption that any measured spectral emission could be given by an arbitrary sum of components from a multitude of energy levels acting independently of each other. As a result, single isolated TSC emissions have often been interpreted as the result of the sum of several, not-resolved TSC peaks, with energy levels up to 0.6 eV and capture cross-sections in the range of 10 −14 -10 −17 cm 2 .…”

Section: Discussionmentioning

confidence: 99%

“…To inspect the nature of the energy levels contributing to this broad TSC signal, we have fitted these curves using Equation (8). Figure 5a-c show results: best fits have a dominant component at Tpeak = 360 K, accompanied by two minor components: a shoulder at a higher temperature, which accounts also for the background current measured during cooling, Table 2 Thermally stimulated currents measured after the two priming processes shown in Figure 3a as compared with the one measured with the same sample after storage in ambient light, same T i = 300 K, V b = 5 V and heating and cooling rate β = 0.08 K/s.…”

Section: Thermally Stimulated Currentsmentioning

confidence: 99%

“…To inspect the nature of the energy levels contributing to this broad TSC signal, we have fitted these curves using Equation (8). Figure 5a-c show results: best fits have a dominant component at T peak = 360 K, accompanied by two minor components: a shoulder at a higher temperature, which accounts also for the background current measured during cooling, Table 2 summarizes energy levels E t of defects best fitting to the measured TSC curves of Figure 4, referring to A: long term ambient storage; B: filling time 230 s; C: filling time 640 s. The three TSC spectra are best-fitted with the same defects, with different trap occupancies due to a different filling duration.…”

Section: Thermally Stimulated Currentsmentioning

confidence: 99%

“…Only very few works on the thermally stimulated current technique applied to CsPbBr 3 are available up to now in literature. A study on single crystal CsPbBr 3 samples has been recently published, mainly focussing on the low-temperature range below 300K [8]. In a more recent report, the TSC analysis has been applied to CsPbBr 3 polycrystalline films [9] and the temperature range has been extended to 400 K, to study a wider energy range, including also defects which are active in the temperature range of interest for solar cells and photodetector applications.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Electrically Active Defects in Polycrystalline and Single Crystal Metal Halide Perovskite

et al. 2020

View full text Add to dashboard Cite

We studied electrically active defects in CsPbBr3 polycrystalline films and single crystals samples using the thermally stimulated currents (TSC) technique in the temperature range 100–400 K. Below room temperature, both polycrystalline and single-crystals TSC emission is composed by a quasi-continuum of energy levels in the range 0.1–0.3 eV, and capture cross sections ~10−21 cm2. Above room temperature, TSC analysis reveals the presence of defect states in the range 0.40–0.52 eV only in polycrystalline samples, whereas these intermediate energy states are absent in TSC detected in single crystals. In polycrystalline films, the occupancy changes of an energy level at 0.45 eV strongly influences the room temperature photoconductivity, giving rise to slow transients due to defect passivation. In single-crystals, where intermediate energy states are absent, the photoconductivity response during illumination is almost stable and characterized by fast rise/decay times, a promising result for future applications of this material in photodetection and dosimetry.

show abstract

Section: Thermally Stimulated Currentsmentioning

confidence: 55%

Section: Discussionmentioning

confidence: 99%

Section: Thermally Stimulated Currentsmentioning

confidence: 99%

“…To inspect the nature of the energy levels contributing to this broad TSC signal, we have fitted these curves using Equation (8). Figure 5a-c show results: best fits have a dominant component at T peak = 360 K, accompanied by two minor components: a shoulder at a higher temperature, which accounts also for the background current measured during cooling, Table 2 summarizes energy levels E t of defects best fitting to the measured TSC curves of Figure 4, referring to A: long term ambient storage; B: filling time 230 s; C: filling time 640 s. The three TSC spectra are best-fitted with the same defects, with different trap occupancies due to a different filling duration.…”

Section: Thermally Stimulated Currentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Electrically Active Defects in Polycrystalline and Single Crystal Metal Halide Perovskite

et al. 2020

View full text Add to dashboard Cite

show abstract

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

et al. 2021

View full text Add to dashboard Cite

conversion efficiencies (PCEs) of perovskite solar cells (PeSCs) have already surpassed 25%, [4] which is comparable to current industrial-grade mono-crystalline silicon solar cells. This fantastic efficiency combined with potentially low-cost fabrication makes them more attractive than the most efficient photovoltaic technologies. [5] Similarly, perovskite light-emitting diodes (PeLEDs) are shown to have an extraordinary performance with external quantum efficiencies (EQEs) exceeding 20% in devices made from the solution phase at low temperatures. [6][7][8] We associated these notable improvements on device performance with lessons learned from organic optoelectronics and other semiconductor devices. Typically, many empirical approaches learned from others such as structural optimization, [9] interface engineering, [10] defects passivation, [11] etc., have been considered optimizing the carrier injection/extraction and mitigating undesirable non-radiative recombination losses. [12][13][14][15][16] Nonetheless, there is plenty of room optimizing nonradiative recombination losses in the bulk and at the interfaces to reach the efficiency limits. [17,18] Historically, band misalignments and interfacial defects have been considered the predominant factors responsible for the undesirable recombination at the various interfaces in devices. [19][20][21] In light of band misalignment, the resulting nonradiative recombination losses at the perovskite interfaces cause a substantial reduction in open-circuit voltages (V oc ) of the PeSCs, [14] mainly because of charge extraction suppression. For example, an energy barrier height of >0.1 eV is sufficient to block the extraction of majority carriers and to block the minority carriers from entering the undesirable transport layer, resulting in efficiency losses. [22] The presence of a charge injection barrier is also known to impact the turn-on voltage and device efficiency of PeLEDs. [23] Moreover, the deep-level defect-assisted recombination provides an additional path for intrinsic loss of charge carriers. [24][25][26] However, the origin and distribution of deep-level defects, a kind of defect that are far away from the band edge and can trap charge carriers, are highly debated topics. To date, there are several experimental observations confirming that a considerable density of deep-level defects retains at the interfaces of both the single-crystal and polycrystalline devices, and some surface passivation strategies can considerably eliminate the defects on the surfaces. [27][28][29] Based on photoemission Surfaces and heterojunction interfaces, where defects and energy levels dictate charge-carrier dynamics in optoelectronic devices, are critical for unlocking the full potential of perovskite semiconductors. In this progress report, chemical structures of perovskite surfaces are discussed and basic physical rules for the band alignment are summarized at various perovskite interfaces. Common perovskite surfaces are typically decorated by various compositional and structur...

show abstract

Ultrasensitive and Robust 120 keV Hard X‐Ray Imaging Detector based on Mixed‐Halide Perovskite CsPbBr₃₋_nI_n Single Crystals

et al. 2022

View full text Add to dashboard Cite

In particular, various X-ray applications with different energies result in different requirements for the detector. For instance, both X-ray diffraction (XRD) and X-ray fluorescence mainly need to detect X-rays with energies lower than 10 keV in scientific research. In contrast, X-rays with energy of 25-50 keV are used to produce images in mammography and chest radiography, [4] while computed tomography (CT) is equipped with digital X-ray image detectors with energy of 80-150 keV. [5,6] Current semiconductor materials such as Si, α-Se, HgI 2 , PbI 2 , and CdZnTe (CZT) are widely applied in direct detectors but suffer from some drawbacks. [7][8][9] Si and α-Se detectors have small attenuation coefficients for light atoms that limit the detection of X-rays to less than 50 keV. HgI 2 and PbI 2 detectors have large leakage currents and poor stability. A commercial CZT detector, which has excellent energy resolution and good photopeak efficiency, is expensive for single crystal (SC) growth and suffers from defects related to charge trapping. [10] Therefore, it is necessary to explore new materials for high-performance radiation detection.In recent years, metal halide perovskites have attracted increasing attention for room-temperature nuclear radiation detection due to their high atomic number (Cs,55, Pb, 82, Br, 35 and I,53), tunable band gap (E g = 1.56-3 eV), [11,12] high resistivity (R = 10 7 -10 12 Ω cm), [13,14] large mobility lifetime product (μτ = 10 −5 to 10 −2 cm 2 V −1 ), [15,16] and low cost in SC growth. These advantageous properties result in large ray attenuation and increased carrier collection efficiency (CCE) for both perovskite SCs and polycrystalline thin films. However, despite their high sensitivity of ≈10 6 -10 8 µC Gy −1 cm −2 , which is two to seven orders of magnitude higher than that of α-Se (20 µC Gy −1 cm −2 ) and CZT (12 000 µC Gy −1 cm −2 ), [17,18] and extremely low detection limit of 0.61 nGy s −1 , which is four orders of magnitude smaller than regular medical diagnostic requirement of 5.5 εGy s −1 , [19] previous studies conducted using these materials have mainly focused on the detection of soft X-rays with energy of several to tens of keV. [18,[20][21][22][23] Few studies have been performed on detecting hard X-rays, specifically in the range greater than 100 keV, which is required in CT imaging and positron emission tomography. In fact, the penetration depthsThe relatively low resistivity and severe ion migration in CsPbBr 3 significantly degrade the performance of X-ray detectors due to their high detection limit and current drift. The electrical properties and X-ray detection performances of CsPbBr 3 −nIn single crystals are investigated by doping the iodine atoms into the melt-grown CsPbBr 3 . The resistivity of CsPbBr 3 −nIn single crystals increases from 3.6 × 10 9 (CsPbBr 3 ) to 2.2 × 10 11 (CsPbBr 2 I) Ω cm, restraining the leak current and decreasing the detection limit of the detector. Additionally, CsPbBr 3 −nIn single crystals exhibit stable dark currents, arising fro...

show abstract

Determination of Defect Levels in Melt-Grown All-Inorganic Perovskite CsPbBr₃ Crystals by Thermally Stimulated Current Spectra

Cited by 50 publications

References 42 publications

Electrically Active Defects in Polycrystalline and Single Crystal Metal Halide Perovskite

Electrically Active Defects in Polycrystalline and Single Crystal Metal Halide Perovskite

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

Ultrasensitive and Robust 120 keV Hard X‐Ray Imaging Detector based on Mixed‐Halide Perovskite CsPbBr₃₋_nI_n Single Crystals

Contact Info

Product

Resources

About

Determination of Defect Levels in Melt-Grown All-Inorganic Perovskite CsPbBr3 Crystals by Thermally Stimulated Current Spectra

Cited by 50 publications

References 42 publications

Electrically Active Defects in Polycrystalline and Single Crystal Metal Halide Perovskite

Electrically Active Defects in Polycrystalline and Single Crystal Metal Halide Perovskite

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

Ultrasensitive and Robust 120 keV Hard X‐Ray Imaging Detector based on Mixed‐Halide Perovskite CsPbBr3−nIn Single Crystals

Contact Info

Product

Resources

About

Determination of Defect Levels in Melt-Grown All-Inorganic Perovskite CsPbBr₃ Crystals by Thermally Stimulated Current Spectra

Ultrasensitive and Robust 120 keV Hard X‐Ray Imaging Detector based on Mixed‐Halide Perovskite CsPbBr₃₋_nI_n Single Crystals