Low-bandgap mixed tin–lead iodide perovskites with reduced methylammonium for simultaneous enhancement of solar cell efficiency and stability

Li, Chongwen; Song, Zhaoning; Chen, Cong; Xiao, Chuanxiao; Subedi, Biwas; Harvey, Steven P.; Shrestha, Niraj; Subedi, Kamala Khanal; Chen, Lei; Liu, Dachang; Li, You; Kim, Yong-Wah; Jiang, Chun‐Sheng; Heben, Michael J.; Zhao, Dewei; Ellingson, Randy J.; Podraza, Nikolas J.; Al‐Jassim, Mowafak; Yan, Yanfa

doi:10.1038/s41560-020-00692-7

Cited by 191 publications

(221 citation statements)

References 48 publications

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“…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.…”

mentioning

confidence: 86%

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

129

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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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mentioning

confidence: 86%

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

129

128

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“…[ 1–4 ] The power conversion efficiency (PCE) of lead (Pb) based perovskite solar cells (PVSCs) has surged to certified 25.5%, continuously approaching their Shockley‐Queisser (SQ) limit efficiency, which makes it strongly competitive for the next generation of photovoltaic technology. [ 5–11 ]…”

Section: Introductionmentioning

confidence: 99%

Suppression of Nonradiative Recombination by Vacuum‐Assisted Process for Efficient Lead‐Free Tin Perovskite Solar Cells

Wan

Ren

Lai

et al. 2021

Adv Materials Inter

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Power conversion efficiency (PCE) of lead (Pb)‐free tin (Sn)‐based perovskite solar cells (PVSCs) is much lower than that of their Pb‐based counterparts, which is mainly attributed to large open‐circuit voltage (VOC) loss and poor fill factor (FF). In this work, a strategy via vacuum‐assisted treatment of the Sn perovskite layer to self‐heal defects in Sn perovskite is reported, leading to suppression of nonradiative recombination and enhancement of carrier transport capability. Using this method, a maximum PCE of 10.3% is obtained for dual FA‐MA (MA = methylammonium and FA = formamidinium) cation Sn‐based PVSCs with an improved VOC of 0.631 V and FF of 75.5%. This work suggests a facile approach to finely inhibit the defects in the bulk or at interfaces for Sn‐based devices and further facilitate development of highly efficient Sn‐based PVSCs.

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“…Other researchers have proved that similarly to halide doping, the addition of antioxidants and ascorbic acids such as tin fluoride (SnF 2 ), tin sulfide (SnS), quaternary ammonium halide (Me 4 NBr), tetramethylammonium iodide (Me 4 NI), methylammonium bromide (MABr), lead thiocyanate (Pb(SCN) 2 ), and other thiocyanate (SCN) salts can improve the perovskite film quality [31]. They ascribed this to reductive additives that do not only prevent Sn 2+ oxidation, but also promote the crystallization growth through strong coordination between PbI 2 /SnI 2 and an organic cation or a combination of organic cations which allows the complete interaction and conversion of metal halides into perovskite [53][54][55][56][57][58][59][60][61].…”

Section: Of 16mentioning

confidence: 99%

“…This reduces the free hole concentration and electron density, which leads to an improved diffusion length of up to 3 µm [31]. Other attempts, such as the deposition of ultrathin bulk-heterojunction (BHJ) organic semiconductor layer as an intermediary between the hole transport layer (HTL) and the mixed low bandgap perovskite to minimize the energy loss by reducing energy level mismatch and passivating defects in the HTL/perovskite interface have been reported [58,[61][62][63].…”

Section: Of 16mentioning

confidence: 99%

Chemical Vapor Deposited Mixed Metal Halide Perovskite Thin Films

et al. 2021

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In this article, we used a two-step chemical vapor deposition (CVD) method to synthesize methylammonium lead-tin triiodide perovskite films, MAPb1−xSnxI3, with x varying from 0 to 1. We successfully controlled the concentration of Sn in the perovskite films and used Rutherford backscattering spectroscopy (RBS) to quantify the composition of the precursor films for conversion into perovskite films. According to the RBS results, increasing the SnCl2 source amount in the reaction chamber translate into an increase in Sn concentration in the films. The crystal structure and the optical properties of perovskite films were examined by X-ray diffraction (XRD) and UV-Vis spectrometry. All the perovskite films depicted similar XRD patterns corresponding to a tetragonal structure with I4cm space group despite the precursor films having different crystal structures. The increasing concentration of Sn in the perovskite films linearly decreased the unit volume from about 988.4 Å3 for MAPbI3 to about 983.3 Å3 for MAPb0.39Sn0.61I3, which consequently influenced the optical properties of the films manifested by the decrease in energy bandgap (Eg) and an increase in the disorder in the band gap. The SEM micrographs depicted improvements in the grain size (0.3–1 µm) and surface coverage of the perovskite films compared with the precursor films.

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Low-bandgap mixed tin–lead iodide perovskites with reduced methylammonium for simultaneous enhancement of solar cell efficiency and stability

Cited by 191 publications

References 48 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%

Suppression of Nonradiative Recombination by Vacuum‐Assisted Process for Efficient Lead‐Free Tin Perovskite Solar Cells

Chemical Vapor Deposited Mixed Metal Halide Perovskite Thin Films

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