Emission Enhancement and Intermittency in Polycrystalline Organolead Halide Perovskite Films

Li, Cheng; Zhong, Yu; Melo-Luna, Carlos A.; Unger, Thomas; Deichsel, Konstantin; Gräser, Anna; Köhler, Jürgen; Köhler, Anna; Hildner, Richard; Huettner, Sven

doi:10.3390/molecules21081081

Cited by 37 publications

(42 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[35,37,38,[63][64][65] These reports are in agreement with our observation that especially the surface of sol-eng films with small grains and high surface defect density (evidenced by the very low PL intensity) degrades on a much faster timescale as compared to PbAc 2 . It is likely that areas of higher defect density (for example, iodine vacancies) are more susceptible to oxygen-induced degradation.…”

Section: Role Of Grain Boundaries In Oxygen Induced Degradationsupporting

confidence: 91%

Role of Microstructure in Oxygen Induced Photodegradation of Methylammonium Lead Triiodide Perovskite Films

Sun

Faßl

Becker‐Koch

et al. 2017

Advanced Energy Materials

212

210

View full text Add to dashboard Cite

photovoltaic technology, where lifetimes greater than 25 years are required. [2] Although the issue of device stability has attracted increased attention of the photovoltaic research community in the last two years, reports that systematically study the fundamental causes (e.g., heat, electrical stress, humidity, oxygen, (UV) light, chemical precursors, processing conditions, influence of film quality and morphology) and mechanisms limiting the material and device stability remain scarce. [2][3][4][5] While the degradation of methylammonium lead iodide (MAPbI 3 ) in humid air has been studied experimentally as well as theoretically and was long thought to be the main factor for material degradation in ambient environment, [6][7][8][9][10][11][12][13][14][15] studies exploring the influence of oxygen and light on the solar cell performance have only recently been reported. [16][17][18][19][20] It has been shown that photoexcited electrons in the perovskite layer can form superoxide (O 2 − ) via electron transfer to molecular oxygen, which through deprotonation of the methylammonium cation in turn results in irreversible material degradation. The severity of the degradation has been linked to the efficiency of electron extraction via the electron extracting layer (EEL): devices employing a compact-TiO 2 /mesoporous Al 2 O 3 or compact-TiO 2 as EELs degraded in dry air on a timescale of less than 1 h, while with the use of a mesoporous TiO 2 layer, an EEL which results in faster electron extraction, the lifetimes were significantly increased. However, in these reports only the degradation of complete photovoltaic device was reported, with limited information on the degradation of the perovskite active layer itself and the impact of its microstructure was not identified.In this work, we systematically study the degradation of MAPbI 3 films under precisely controlled exposure to various oxygen levels (0-20%) under simulated sunlight in order to shed light on the progression of perovskite degradation under these conditions. We investigate two types of perovskite layers that are formed using different fabrication methods. The two recipes allow us to include the effect of layer microstructure on the dynamics of oxygen-induced degradation. We characterize the electronic, optical, compositional, and structural properties of the degraded perovskite films and correlate these results This paper investigates the impact of microstructure on the degradation rate of methylammonium lead triiodide (MAPbI 3 ) perovskite films upon exposure to light and oxygen. By comparing the oxygen induced degradation of perovskite films of different microstructure-fabricated using either a lead acetate trihydrate precursor or a solvent engineering technique-it is demonstrated that films with larger and more uniform grains and better electronic quality show a significantly reduced degradation compared to films with smaller, more irregular grains. The effect of degradation on the optical, compositional, and microstructural properties of the perovsk...

show abstract

Section: Role Of Grain Boundaries In Oxygen Induced Degradationsupporting

confidence: 91%

Role of Microstructure in Oxygen Induced Photodegradation of Methylammonium Lead Triiodide Perovskite Films

Sun

Faßl

Becker‐Koch

et al. 2017

Advanced Energy Materials

212

210

View full text Add to dashboard Cite

show abstract

“…A, second, more probable explanation is local improvement of crystallinity due to laser annealing that decreases the nonradiative decay rate, something that will need to be studied further. A similar increase has also been reported for MAPbI 3 and attributed to trap filling, migration of defects, or chemical passivation of the defects . For the sake of discussion here, we consider the more luminescent situation as “damage,” since, eventually, the original state is recovered, i.e., self‐healing occurs.…”

supporting

confidence: 64%

Self‐Healing Inside APbBr₃ Halide Perovskite Crystals

et al. 2018

View full text Add to dashboard Cite

Self-healing, where a modification in some parameter is reversed with time without any external intervention, is one of the particularly interesting properties of halide perovskites. While there are a number of studies showing such self-healing in perovskites, they all are carried out on thin films, where the interface between the perovskite and another phase (including the ambient) is often a dominating and interfering factor in the process. Here, self-healing in perovskite (methylammonium, formamidinium, and cesium lead bromide (MAPbBr , FAPbBr , and CsPbBr )) single crystals is reported, using two-photon microscopy to create damage (photobleaching) ≈110 µm inside the crystals and to monitor the recovery of photoluminescence after the damage. Self-healing occurs in all three perovskites with FAPbBr the fastest (≈1 h) and CsPbBr the slowest (tens of hours) to recover. This behavior, different from surface-dominated stability trends, is typical of the bulk and is strongly dependent on the localization of degradation products not far from the site of the damage. The mechanism of self-healing is discussed with the possible participation of polybromide species. It provides a closed chemical cycle and does not necessarily involve defect or ion migration phenomena that are often proposed to explain reversible phenomena in halide perovskites.

show abstract

“…activation energy, band bending, etc), ionic migration is considered as the dominate factor, associated with not only hysteresis [68] but also other unusual emission and capacity behaviors [69][70][71][72][73]. Briefly, as illustrated in Figure 9, under external electrical field, ions are driven towards the opposite interfaces (perovskite/ETL and perovskite/HTL, respectively).…”

Section: Ion Migrationmentioning

confidence: 99%

Origins and mechanisms of hysteresis in organometal halide perovskites

Guerrero

Zhong

et al. 2017

J. Phys.: Condens. Matter

Self Cite

View full text Add to dashboard Cite

Inorganic–organic halide organometal perovskites, such as CH3NH3PbI3 and CsPbI3, etc, have been an unprecedented rising star in the field of photovoltaics since 2009, owing to their exceptionally high power conversion efficiency and simple fabrication processability. Despite its relatively short history of development, intensive investigations have been concentrating on this material; these have ranged from crystal structure analysis and photophysical characterization to performance optimization and device integration, etc. Yet, when applied in photovoltaic devices, this material suffers from hysteresis, that is, the difference of the current–voltage (I–V) curve during sweeping in two directions (from short-circuit towards open-circuit and vice versa). This behavior may significantly impede its large-scale commercial application. This Review will focus on the recent theoretical and experimental efforts to reveal the origin and mechanism of hysteresis. The proposed origins include (1) ferroelectric polarization, (2) charge trapping/detrapping, and (3) ion migration. Among them, recent evidence consistently supports the idea that ion migration plays a key role for the hysteretic behavior in perovskite solar cells (PSCs). Hence, this Review will summarize the recent results on ion migration such as the migrating ion species, activation energy measurement, capacitive characterization, and internal electrical field modulation, etc. In addition, this Review will also present the devices with alleviation/elimination of hysteresis by incorporating either large-size grains or phenyl-C61-butyric acid methyl ester molecules. In a different application, the hysteretic property has been utilized in photovoltaic and memristive switching devices. In sum, by examining these three possible mechanisms, it is concluded that the origin of hysteresis in PSCs is associated with a combination of effects, but mainly limited by ion/defect migration. This strong interaction between ion motion and free charge carrier transport can be modulated by the prevalent crystalline structure, chemical passivation, and an external photo/electrical field.

show abstract

Emission Enhancement and Intermittency in Polycrystalline Organolead Halide Perovskite Films

Cited by 37 publications

References 55 publications

Role of Microstructure in Oxygen Induced Photodegradation of Methylammonium Lead Triiodide Perovskite Films

Role of Microstructure in Oxygen Induced Photodegradation of Methylammonium Lead Triiodide Perovskite Films

Self‐Healing Inside APbBr₃ Halide Perovskite Crystals

Origins and mechanisms of hysteresis in organometal halide perovskites

Contact Info

Product

Resources

About

Emission Enhancement and Intermittency in Polycrystalline Organolead Halide Perovskite Films

Cited by 37 publications

References 55 publications

Role of Microstructure in Oxygen Induced Photodegradation of Methylammonium Lead Triiodide Perovskite Films

Role of Microstructure in Oxygen Induced Photodegradation of Methylammonium Lead Triiodide Perovskite Films

Self‐Healing Inside APbBr3 Halide Perovskite Crystals

Origins and mechanisms of hysteresis in organometal halide perovskites

Contact Info

Product

Resources

About

Self‐Healing Inside APbBr₃ Halide Perovskite Crystals