Perovskite Solar Cells: Understanding the Role of Cesium and Rubidium Additives in Perovskite Solar Cells: Trap States, Charge Transport, and Recombination (Adv. Energy Mater. 16/2018)

Hu, Yinghong; Hutter, Eline M.; Rieder, Philipp; Grill, Irene; Hanisch, Jonas; Aygüler, Meltem F.; Hufnagel, Alexander G.; Handloser, Matthias; Bein, Thomas; Hartschuh, Achim; Tvingstedt, Kristofer; Dyakonov, Vladimir; Baumann, Andreas; Savenije, Tom J.; Petrus, Michiel L.; Docampo, Pablo

doi:10.1002/aenm.201870073

Cited by 6 publications

(8 citation statements)

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“…For the considered sample, values vary between 4.2 × 10 14 cm –3 for sample P 2 and 8 × 10 15 cm –3 for sample P 3 . The latter is consistent with N T values previously reported in perovskite absorbers. ,, The influence of traps on the charge carrier kinetics in a pulsed excitation regime mainly happens through the photodoped charges that they fix in the valence band by trapping electrons on the long term. ,, This is mainly described by their concentration N T , in which the lower value in P 2 and P 3 confirms the effective trap passivation through cation substitution previously observed. , What is more, the good correlation between the effect of chemical composition on N T and V oc values underlines the significant role of these traps in solar cell operation. On contrary to N T values, R eh * coefficients are quite constant and stick to low values for every sample and photon recycling corrected values elevate up to 10 –9 cm 3 /s, notably close to the expected radiative recombination rate .…”

Section: Discussionsupporting

confidence: 90%

Slow Diffusion and Long Lifetime in Metal Halide Perovskites for Photovoltaics

Bercegol

Ramos

Rebai³

et al. 2018

J. Phys. Chem. C

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Metal halide perovskites feature excellent absorption, emission and charge carrier transport properties. These materials are therefore very well suited for photovoltaics applications where there is a growing interest. Still, questions arise when looking at the unusual long carrier lifetime that, regarding the micrometric diffusion length, would imply a very low diffusion coefficient as compared to commonly used photovoltaic absorbers. In this paper, we provide an experimental insight into this long lifetime of charge carriers in slowmotion. Our approach relies on an improved model to analyze time-resolved photoluminescence decays at multiple fluence levels that includes charge carrier transport, photon recycling, and traps dynamics. The model is verified on different interface properties. Moreover, we investigate various perovskite absorbers such as mixed alloys with cesium content. For most of the perovskite based materials we analyzed, the band-to-band recombination rate remains close to the radiative limit, leading to the expected submicrosecond lifetime. The slow diffusion of charge carriers is observed with values of the diffusion coefficient D around 5x10 -3 cm 2 /s. Nonetheless, the power conversion efficiency remains high. The observations might be related to the debated coexistence of a direct and indirect bandgap slowing down the recombination process. PV characterization

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Section: Discussionsupporting

confidence: 90%

Slow Diffusion and Long Lifetime in Metal Halide Perovskites for Photovoltaics

Bercegol

Ramos

Rebai³

et al. 2018

J. Phys. Chem. C

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“…In regard to materials, all-inorganic perovskites have higher thermal stability than the hybrid (methylammoniumand formamidinium-based) analogues. [55,56] The alkali-metal additives can effectively passivate defects without inducing loss in charge-carrier mobility, [57] thus leading to remarkable improvement of device brightness. PL measurements of perovskite films before and after operation ( Figure S22, Supporting Information) indicate that the introduction of Rb + and K + ions also improved the thermal stability of perovskite film.…”

Section: Resultsmentioning

confidence: 99%

Suppressing Ion Migration Enables Stable Perovskite Light‐Emitting Diodes with All‐Inorganic Strategy

Zhang

Yuan

et al. 2020

Adv Funct Materials

100

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2001834 (1 of 8) mobility, and low cost, make this emergent technology very promising. [1-9] Recently, near-infrared and green PeLEDs with external quantum efficiency (EQE) over 20% were reported, [10-13] signifying that we are one step closer to the practical application of PeLEDs in lighting and displays. Several metrics are generally used to assess the performance of PeLEDs. EQE and lifetime are of particular importance among them. Besides, brightness is an intuitive criterion for visible LEDs. [14-16] Most of the previous studies have not yet matched these three metrics simultaneously. For example, the green PeLED with the to-date record-high EQE of 20.3%, the record of PeLEDs so far, had a maximal luminance of 14 000 cd m −2 and 46 h lifetime (measured at continual mode of 100 cd m −2); [11] while for the most stable green PeLED to date (lifetime 250 h measured at initial brightness of 100 cd m −2), the EQE and luminance were 10.5% and 16 436 cd m −2 , respectively. [17] Critical factors that affect the PeLEDs lifetime include the materials stability, the intrinsic defects in perovskites, and most importantly, ion migration within devices. [18-21] Stable perovskites with high luminescence are essential to achieve PeLEDs with both high stability and efficiency. Hybrid organicinorganic perovskites degrade quickly against the heat and environmental moisture. All-inorganic perovskites usually have higher stability, but their PLQY is generally unsatisfactory because of the relatively low film quality. [22] The nonuniform morphology of perovskite films and the high density of defect states are detrimental to the electroluminescence (EL) emission. Intrinsic defects can mediate charge-carrier trapping thus leading to nonradiative recombination loss, which is harmful to the device performance. For efficient PeLEDs with high stability, many efforts have been devoted to reduce the trap states in perovskite films. Introducing large organic ligands is a widely adopted approach, as it can passivate defects and achieve a relatively high film quality by stabilizing the perovskite surfaces or facilitating the formation of low-dimensional perovskites. [13,23-27] Through optimal composition and phase engineering, Yang et al. achieved an EQE of 14.36% and an improved stability for green PeLEDs with quasi-2D perovskites. [27] Meanwhile, Xu et al. demonstrated a highly efficient and stable PeLEDs through the rational design of passivation molecules. [13] The improved stability results from a combination of reduced Joule heating caused by the high efficiency and the suppression of ion migration due to reduced defect density.

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“…Furthermore, different concentration of RbI (0.5-2%) for all in-organic perovskite (CsPbI 2 Br) was analyzed in the construction of high-efficiency, low cost, and improved air stability of hybrid PSCs [67]. Compared with un-doped CsPbI 2 Br perovskite films, excellent crystallinity, improved surface morphology, and enhanced absorbance were shown after incorporation of RbI, as had been reported in previously published studies [69,91].…”

Section: Role Of Incorporating Rubidium Ions In Hpmmentioning

confidence: 56%

A review on advances in doping with alkali metals in halide perovskite materials

et al. 2021

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Recent progress in doping of halide perovskite materials (HPM) by using targeted elements has provided a dimension beyond structural and compositional modification, for achieving desired properties and resulting device performance. Herein doping of alkali metal ions (Li+, Na+, K+, Rb+, and Cs+) in three-dimensional HPM is reviewed to lay a particular focus on advances in synthesis, doping-induced changes in optical and electrical properties, and their optoelectronic applications. The introduction of alkali metals in HPM shows an effective route for improved morphology, suppressed ion migration, reduction in non-radiative recombination, passivation of bulk and interface defects, and increased thermal stability. In the end, we provide our perspective that the effect of alkali metal incorporation on the efficiency and stability of HPM should be further investigated via in-situ characterization methods and doped HPM should be considered for more functional applications. Graphical abstract

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Perovskite Solar Cells: Understanding the Role of Cesium and Rubidium Additives in Perovskite Solar Cells: Trap States, Charge Transport, and Recombination (Adv. Energy Mater. 16/2018)

Cited by 6 publications

References 0 publications

Slow Diffusion and Long Lifetime in Metal Halide Perovskites for Photovoltaics

Slow Diffusion and Long Lifetime in Metal Halide Perovskites for Photovoltaics

Suppressing Ion Migration Enables Stable Perovskite Light‐Emitting Diodes with All‐Inorganic Strategy

A review on advances in doping with alkali metals in halide perovskite materials

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