Approaching the Shockley–Queisser limit for fill factors in lead–tin mixed perovskite photovoltaics

Jayawardena, K. D. G. Imalka; Bandara, R. M. I.; Monti, Maurizio; Butler-Caddle, Edward; Pichler, Thomas; Shiozawa, Hidetsugu; Wang, Zhiping; Jenatsch, Sandra; Hinder, Steven J.; Masteghin, Mateus G.; Patel, M. Tahir; Thirimanne, H.M.; Zhang, Wei; Sporea, Radu A.; Lloyd‐Hughes, James; Silva, S.R.P.

doi:10.1039/c9ta10543c

Cited by 37 publications

(43 citation statements)

References 37 publications

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“…Also, a post-treatment on perovskite films by toluene rinsing has been reported to further remove Sn(IV). [17] To uncover the toluene rinsing effect on solar cell performance and differentiate it from the EDA coating effect, we analyzed the PCE of devices without EDA coverage. Little improvement in PCE was noticed which can be ascribed to better FF, however, no change in V oc was noticed.…”

Section: Resultsmentioning

confidence: 99%

“…[13] In another work, the surface passivation of Sn-Pb perovskite films by phenethylammonium (PEA) cation has been described that led to the formation of a 2D capping layer resulting in the stability of the films against oxidation. [14] Jayawardena et al, [17] also revealed the passivation effect of guanidinium bromide (GuaBr) leading to the better energy alignment between the perovskite and electron transport layer which enhances the fill factor drastically near to the SQ limit. It is well known that the better energy alignment between perovskite and charge transport layers is key in improving the PSC performance due to the reduction in carrier recombination and the better charge transfer at the interface.…”

Section: Introductionmentioning

confidence: 99%

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Tin‐Lead Perovskite Fabricated via Ethylenediamine Interlayer Guides to the Solar Cell Efficiency of 21.74%

Kapil

Bessho

Maekawa

et al. 2021

Advanced Energy Materials

126

128

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terms of employing the ideal bandgap absorber layer in PSC, the tin-lead (Sn-Pb) mixed PSCs are now getting attention with the additional benefit of utilizing them in tandem solar cell technology. [8][9][10] In recent years, various research groups have demonstrated power conversion efficiencies (PCEs) of more than 20% by employing Sn-Pb PSCs. [9,[11][12][13][14] However, PCE of Sn-Pb mixed PSCs is still lagging behind their Pb counterparts, especially in terms of open-circuit voltage (V oc ) loss, which is conventionally described as the deficit from the bandgap, is less than 0.3 V for the efficient Pb-PSCs. [4][5][6] Therefore, in the recent past, the efforts are directed toward finding the solutions to overcome the V oc loss. Researchers around the world are trying to address the problem by solving the issues related to the physical properties of the Sn-Pb perovskite films such as short carrier lifetime, [12] large Urbach energy, [11] high trap density, and most importantly the rapid oxidation of Sn 2+ to Sn 4+ . [9,13,14] The focus has been on improving the physical properties by employing different thin film formation strategies. Tong et al., [12] demonstrated the drastic improvement in optoelectronic properties such as the increase in carrier lifetime of more than 1 µs and carrier diffusion length of longer than 1 µm with the incorporation of bulky guanidinium thiocyanate (GuaSCN) into the perovskite films that led to the first research report of more than 20% PCE in Sn-Pb PSCs with a V oc loss of 0.42 V. The increase in PSC performance is assigned to the passivation by the formation of a 2D structure at the grain boundaries that also suppresses the formation of Sn vacancies. This kind of improvement in solar cell performance is the same observation as reported in the case of pure Pb-containing PSCs. [15] Our group also showed the effect of the decrease in trap densities, at the surface and bulk, by using strain engineering, steering to the PCE of 20.4%, and V oc loss of less than 0.50 V. [11] Recently, Li et al., [16] also demonstrated the importance of surface and grain boundary passivation by the formation of 1D pyrrolidine perovskite, a V oc loss of 0.41 V is reported. Lin et al., [9] addressed the oxidation problem in Sn-Pb precursor solution. The Sn metal is introduced as a reducing agent in precursor solution that decreased concentration of Sn 4+ (Sn 4+ + Sn→ 2Sn 2+ ) in the precursor solution before the film formation, Tin-lead perovskite solar cells (PSCs) show inferior power conversion efficiency (PCE) than their Pb counterparts mainly because of the higher open-circuit voltage (V oc ) loss. Here, it is revealed that the p-type surface of perovskite transforms to n-type, based on post-treatment by a Lewis base, ethylenediamine. This approach forms a graded band structure owing to the rise of the Fermi-energy level at the surface of the perovskite layer, and increases the built-in potential from 0.56 to 0.76 V, which increases the V oc by more than 100 mV. It is demonstrated that EDA can lower the ...

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tin‐Lead Perovskite Fabricated via Ethylenediamine Interlayer Guides to the Solar Cell Efficiency of 21.74%

Kapil

Bessho

Maekawa

et al. 2021

Advanced Energy Materials

126

128

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“…In most other reports, PbSn perovskites with similar bandgaps delivered even lower short‐circuit current (<30 mA cm –2 ). [ 17–19 ] This discrepancy between two apparently similar technologies is not often discussed and it is currently not clear why Sn(II) containing perovskites cannot achieve as high currents as their lead counterparts relative to their SQ limits.…”

Section: Introductionmentioning

confidence: 99%

Universal Current Losses in Perovskite Solar Cells Due to Mobile Ions

Thiesbrummel

Corre

Peña‐Camargo

et al. 2021

Advanced Energy Materials

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Efficient mixed metal lead‐tin halide perovskites are essential for the development of all‐perovskite tandem solar cells, however they are currently limited by significant short‐circuit current losses despite their near optimal bandgap (≈1.25 eV). Herein, the origin of these losses is investigated, using a combination of voltage dependent photoluminescence (PL) timeseries and various charge extraction measurements. It is demonstrated that the Pb/Sn‐perovskite devices suffer from a reduction in the charge extraction efficiency within the first few seconds of operation, which leads to a loss in current and lower maximum power output. In addition, the emitted PL from the device rises on the exact same timescales due to the accumulation of electronic charges in the active layer. Using transient charge extraction measurements, it is shown that these observations cannot be explained by doping‐induced electronic charges but by the movement of mobile ions toward the perovskite/transport layer interfaces, which inhibits charge extraction due to band flattening. Finally, these findings are generalized to lead‐based perovskites, showing that the loss mechanism is universal. This elucidates the negative role mobile ions play in perovskite solar cells and paves a path toward understanding and mitigating a key loss mechanism.

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“…introduced GABr as an additive into Cs 0.05 FA 0.79 MA 0.16 Pb 0.5 Sn 0.5 I 3 perovskites. [ 112 ] The post‐treatment with GABr modified the band alignment and contact of the perovskite/HTL and perovskite/ETL interfaces, enabling better bipolar extraction. The resulting shifts in the conduction band, valence band and Fermi level energies reduce the barrier for both hole and electron transfer from the LTM perovskite absorber to the anode and cathode contacts.…”

Section: Sn‐based Perovskite Solar Cellsmentioning

confidence: 99%

“…The atomic percentage of Sn 4+ decreases in the order of anisole > CB> toluene, and the device performance increases in the order of anisole < CB < toluene, which is further substantiated by the lower impact of parasitic charges for lead‐tin mixed (LTM) PSCs under toluene treatment. [ 112 ] As a result, the champion efficiency they achieved is 11.6%, and the short circuit current density is ∼28 mAcm −2 .…”

Section: Sn‐based Perovskite Solar Cellsmentioning

confidence: 99%

ASnX₃—Better than Pb‐based Perovskite

et al. 2020

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Organic‐inorganic halide perovskite solar cells (PSCs) have drawn tremendous attention as their power conversion efficiency (PCE) has soared to 25.2%. Yet the most efficient halide perovskite materials all contain the toxic element lead (Pb). The search for an alternative element is a crucial research direction. Among all candidates, tin (Sn) appears to be the most promising one for its nontoxicity and physical similarity to lead (Pb). Herein, we review and summarize recent advancements in this emerging research area of Sn‐based perovskites. First, we discuss the photophysical dynamics of the Sn‐based perovskites and the relatively high efficiency of corresponding PSCs and other applications. Then, the attention is focused on the fabrication process and methods to improve the performance of Sn‐based photovoltaic devices. Despite the fact that the stabilities of the materials and related devices are far from perfect, the Sn‐based perovskites are still the best candidates with vast potential among all the Pb‐free perovskites for PSC application.

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Approaching the Shockley–Queisser limit for fill factors in lead–tin mixed perovskite photovoltaics

Abstract: A new post-treatment method for lead–tin mixed perovskites enabling device fill factors approaching 83%.

Cited by 37 publications

References 37 publications

Tin‐Lead Perovskite Fabricated via Ethylenediamine Interlayer Guides to the Solar Cell Efficiency of 21.74%

Tin‐Lead Perovskite Fabricated via Ethylenediamine Interlayer Guides to the Solar Cell Efficiency of 21.74%

Universal Current Losses in Perovskite Solar Cells Due to Mobile Ions

ASnX₃—Better than Pb‐based Perovskite

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Approaching the Shockley–Queisser limit for fill factors in lead–tin mixed perovskite photovoltaics

Abstract: A new post-treatment method for lead–tin mixed perovskites enabling device fill factors approaching 83%.

Cited by 37 publications

References 37 publications

Tin‐Lead Perovskite Fabricated via Ethylenediamine Interlayer Guides to the Solar Cell Efficiency of 21.74%

Tin‐Lead Perovskite Fabricated via Ethylenediamine Interlayer Guides to the Solar Cell Efficiency of 21.74%

Universal Current Losses in Perovskite Solar Cells Due to Mobile Ions

ASnX3—Better than Pb‐based Perovskite

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ASnX₃—Better than Pb‐based Perovskite