Relationship between Lattice Strain and Efficiency for Sn-Perovskite Solar Cells

Nishimura, Kohei; Hirotani, Daisuke; Kamarudin, Muhammad Akmal; Shen, Qing; Toyoda, Taro; Iikubo, Satoshi; Minemoto, Takashi; Yoshino, Kenji; Hayase, Shuzi

doi:10.1021/acsami.9b09564

Cited by 113 publications

(114 citation statements)

References 37 publications

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“…[34] When 0.1 mm EDA was coated on the surface of the perovskite, both the HOMO and LUMO energy have shifted to the deeper energy states indicating the decrease in self-doping as explained previously. [35,36] Interestingly, with the coating of 0.1 mm EDA, the E f has shifted to a value of −4.78 eV which is shallower than E i (−5.0 eV) indicating the n-type character of the film. [34] This change in semiconducting nature can be assigned to the increase in electron concentration contributed by the electron-donating amine group of EDA at the perovskite surface.…”

Section: Resultsmentioning

confidence: 99%

“…We also investigated the strain component (C ε ) and Urbach energy (E u ) in the perovskite film after insertion of Br anion by using Williamson-Hall plot (Figure S14a-d, Supporting Information) and absorption spectra (Figure S14e, Supporting Information) as reported in some of the recent articles. [5,11,36] The larger value of C ε and E u are an indication of the presence of large traps within the perovskite. Hence, with the optimized concentration of Br 2.5 mol% the values of C ε (0.0755) and E u (0.091 eV) were least among all the perovskite films, supporting the best performance of PSCs based on Br-2.5% compared to other Br added solar cells (Figure S14f, Supporting Information).…”

Section: Resultsmentioning

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

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132

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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: Resultsmentioning

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

Self Cite

132

128

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“…It is found that as the tolerance factor t gets closer to 1, the lattice strain of Sn‐based MHPs gradually decreases due to the formation tendency of the cubic crystal structure (Figure 3c,d). [ 37 ] Because the carrier mobility increases as the lattice strain decreases, the increased lattice strain, when t value gets away from 1, will decrease the carrier mobility and reduce the PCE of the corresponding PSCs (Figure 3e). Notably, by optimizing the t value to be close to 1 using EA, PSCs based on EA 0.1 (FA 0.75 MA 0.25 ) 0.9 SnI 3 film with the lowest lattice strain shows a champion PCE of 5.41%.…”

Section: Strain Engineering In Mhps and Their Pscsmentioning

confidence: 99%

Strain Engineering of Metal–Halide Perovskites toward Efficient Photovoltaics: Advances and Perspectives

Gu¹,

Li²,

Chao³

et al. 2021

Solar RRL

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Due to the impressive optoelectronic properties, metal–halide perovskites (MHPs) have drawn much attention in the field of next‐generation photovoltaics, and perovskite solar cells (PSCs) based on MHPs as light absorbers have reached a certified power conversion efficiency (PCE) of 25.5% in 2020. Despite the great progress, it is still challenging to fabricate high‐quality MHP films. Due to the “soft” ionic nature of MHPs, their polycrystalline films suffer from inevitable residual strain, which is found to not only be fatal to photovoltaic performance of PSCs, but also seriously accelerate the degradation of MHP film. As a result, understanding of strain in MHPs and the key role of strain engineering in improving the photovoltaic performance of PSCs have recently been extensively investigated. Herein, the recent progress of strain engineering in MHPs and their PSCs is systematically summarized. First, the origin of strain in MHPs and the impact of strain on the optoelectronic characteristics of MHPs are carefully discussed. Thereafter, the up‐to‐date studies focusing on strain engineering in PSCs are comprehensively reviewed. At last, the current challenges and future prospects in this field are highlighted.

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“…Meanwhile, the effect of strain on the optoelectronic properties and ion migration of MHPs has also been investigated. [ 152–167 ] Zhao et al. discovered that lattice strain significantly affects the stability of MHPs ( Figure a) via modifying the activation energy of ion migration; [ 152 ] a larger lattice strain reduces the activation of ion migration, promoting the degradation of CH 3 NH 3 PbI 3 films.…”

Section: Ferroicity Strain and Optoelectronic Performancementioning

confidence: 99%

Ferroic Halide Perovskite Optoelectronics

Liu

Kim

Ievlev

et al. 2021

Adv Funct Materials

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Metal halide perovskites (MHPs) as one of the most active materials gained tremendous attention in the past decade because of their outstanding performance in optoelectronics. Owing to their perovskite structure, ferroelectricity is anticipated in this class of materials. However, whether MHPs are ferroelectric or not remains elusive. Recently, discussion regarding ferroelasticity in MHPs has been also raised. In addition, ionic motion and structural dynamics are well known in MHPs. The interplay of these phenomena including electric polarization, strain, ionic motion, and structural dynamics can have a significant impact on optoelectronics. Therefore, understanding the mechanism behind these phenomena and their interactions is critical in addressing the controversy about ferroicity of MHPs and developing functional devices. Here, the current findings about MHP's ferroicity are summarized and evaluated and a perspective for the future is provided. It is suggested that ionic motion and associated phenomena, coupled with ferroic behavior, are the main drivers behind MHPs functionality. The challenges are also discussed in probing MHPs’ ferroicity and what new measurement modalities are needed to fully understand and characterize MHP behavior. Finally, it is discussed how ferroic and strain can affect the optoelectronic performance of MHPs and how they can be used for engineering of higher performance devices.

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Relationship between Lattice Strain and Efficiency for Sn-Perovskite Solar Cells

Cited by 113 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%

Strain Engineering of Metal–Halide Perovskites toward Efficient Photovoltaics: Advances and Perspectives

Ferroic Halide Perovskite Optoelectronics

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