Elimination of Light-Soaking Effect in Hysteresis-Free Perovskite Solar Cells by Interfacial Modification

Yang, Cheng; Hu, Ziyang; Gao, Can; Wang, Yanyan; Zhang, Houcheng; Wang, Jun; Zhang, Jing; Zhou, Xingfei; Zhu, Yuejin

doi:10.1021/acs.jpcc.9b10022

Cited by 20 publications

(19 citation statements)

References 64 publications

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“…The enhanced photovoltaic performance has also been observed in both organic−inorganic and all-inorganic perovskite systems without Br content. 47,48 For the 33% Br device, the loss of J sc is about 2.4 mA/cm 2 after 10 min illumination and recovery, while the V oc is not changed, as shown in Figure 8d. Both the current and voltage in the 50% Br device are seriously degraded after illumination.…”

Section: ■ Results and Discussionmentioning

confidence: 86%

Stability in Photoinduced Instability in Mixed-Halide Perovskite Materials and Solar Cells

Fang¹,

Yao²,

Hu³

et al. 2021

J. Phys. Chem. C

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Bandgap variation due to photoinduced instability in mixed-halide perovskites presents a major obstruction for their future commercial application. Here, the photoinduced process including ever-present halide-ion migration and consequent halide phase segregation is disclosed. We demonstrate that photoinduced halide-ion migration serves as a self-healing behavior, enabling an efficient yield of photoluminescence (PL) without peak shift. Photoinduced halide phase segregation is not reversible, exhibiting an obvious red-shifted PL spectrum due to the formed smaller-bandgap I-rich phase perovskite. The Br content in mixed-halide perovskite systems determines the transformation from halide-ion migration to halide phase segregation under illumination. By investigation of the relationships between the I-rich phase perovskite and the red-shifted PL spectra, the stable perovskite composition with a critical Br/I ratio is identified regardless of the high Br content in mixed-halide perovskite systems. Halide-ion migration could be a universal origin of photoinduced phase segregation in mixed-halide perovskites and instability of mixed-halide perovskite solar cells. Our result provides a reference for the adjustment of halogen composition of ternary cationic perovskites with excellent photostability.

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Section: ■ Results and Discussionmentioning

confidence: 86%

Stability in Photoinduced Instability in Mixed-Halide Perovskite Materials and Solar Cells

Fang¹,

Yao²,

Hu³

et al. 2021

J. Phys. Chem. C

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“…Summarizing, the positive effects of water [ 51–53 ] and light‐soaking, on the perovskite, [ 73–76 ] which were also reported a few times for devices, can be traced to water extracting H + from CH 3 NH 3 + , serving as catalyst for, and light speeding up H + migration HaPs. Further experiments are needed to check this view and the details of the mechanism(s) involved.…”

Section: Figurementioning

confidence: 99%

Eppur si Muove: Proton Diffusion in Halide Perovskite Single Crystals

et al. 2020

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Halide perovskites, HaPs, can show remarkable to outstanding properties and photovoltaic (PV) devices in which they are the absorber can show excellent performances. [1-4] Apart from the PV results, also light-emission, radiation detection, and other electronics are explored. [5-8] During their relatively short history, numerous questions have arisen about the materials' properties and functions with many central ones still under discussion, such as the proposed idea of defect tolerance which awaits experimental evidence. At the same time, already several observables have been linked to fascinating phenomena, such as anharmonicity [9] and high entropy. [10] Ion migration in HaPs belongs to the latter class and has been widely discussed. Migrating ions modify conductivity and junction architecture with consequences for the overall efficiency of junction devices, such as solar cells. A wide consensus identifies halides, specifically I − and Br − , as the migrating ions, although, still without the gold standard experiment of isotope tracing. Remarkably, with some notable exceptions, there is no mention of contributions of protons to ion migration, although their absence in HaPs containing CH 3 NH 3 + (MA +) and HC(NH 2) 2 (FA +) (as the A cation in ABX 3) would be remarkable. In the past years of our research on dynamic effects in halide perovskites (self-healing and ion Ion diffusion affects the optoelectronic properties of halide-perovskites (HaPs). Until now, the fastest diffusion has been attributed to the movement of the halides, largely neglecting the contribution of protons, on the basis of computed density estimates. Here, the process of proton diffusion inside HaPs, following deuterium-hydrogen exchange and migration in MAPbI 3 , MAPbBr 3 , and FAPbBr 3 single crystals, is proven through D/H NMR quantification, Raman spectroscopy, and elastic recoil detection analysis, challenging the original assumption of halide-dominated diffusion. The results are confirmed by impedance spectroscopy, where MAPbBr 3-and CsPbBr 3-based solar cells respond at very different frequencies. Water plays a key role in allowing the migration of protons as deuteration is not detected in its absence. The water contribution is modeled to explain and forecast its effect as a function of its concentration in the perovskite structure. These findings are of great importance as they evidence how unexpected, waterdependent proton diffusion can be at the basis of the ≈7 orders of magnitude spread of diffusion (attributed to I − and Br −) coefficient values, reported in the literature. The reported enhancement of the optoelectronic properties of HaP when exposed to small amounts of water may be related to the finding.

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“…The corresponding C‐f values are shown in Figure 4b; the low‐frequency (less than 1 kHz) signal corresponds to the accumulation process of electrons and possible ions, involving the defect state at the interface. According to the processing results, the 5ATZ‐processed device offers a significantly reduced capacitance in the low‐frequency region, which proves the effect of reducing the ion accumulation and defect at the interface [51,52] . Generally, hysteresis originates from charge trapping and capacitance at the interface and grain boundaries, which contributes to ion migration.…”

Section: Resultsmentioning

confidence: 89%

Amino‐Linked Conjugated Tetrazole Ring Passivation Strategy for Air‐Processed Perovskite Cells with Predominant Stability and Efficiency

Deng

Zhang

et al. 2021

ChemSusChem

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Perovskite solar cells (PSCs) develop rapidly with certified efficiency over 25.5 %, but there are remaining problems such as defects‐induced recombination and degradation throughout the whole device. Functional organic small molecule passivation strategies are diverse and efficient, enhancing the efficiency and stability of PSCs. Here, 5‐aminotetrazole (5ATZ) was introduced for the first time as an effective passivator, where −NH2 and −NH as active sites interacted with the Pb and I related to vacancy defects in perovskites, anchoring defects and preventing further unavoidable ion migration and device degradation. Furthermore, the extensive π‐electron delocalization around the tetrazole conjugated ring significantly promoted the charge transfer. Therefore, the 5ATZ‐processed PSCs provided enhanced voltage and current, showed superior 19.75 % power conversion efficiency with excellent performance and improved stability, and demonstrated one of the best performances in all‐air preparation to date. The simultaneous multi‐effect passivation strategy of vacancy defects in perovskites will contribute to eliminate obstacles on the road to commercialization of PSCs.

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Elimination of Light-Soaking Effect in Hysteresis-Free Perovskite Solar Cells by Interfacial Modification

Cited by 20 publications

References 64 publications

Stability in Photoinduced Instability in Mixed-Halide Perovskite Materials and Solar Cells

Stability in Photoinduced Instability in Mixed-Halide Perovskite Materials and Solar Cells

Eppur si Muove: Proton Diffusion in Halide Perovskite Single Crystals

Amino‐Linked Conjugated Tetrazole Ring Passivation Strategy for Air‐Processed Perovskite Cells with Predominant Stability and Efficiency

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