Lead‐Free Halide Perovskite Solar Cells with High Photocurrents Realized Through Vacancy Modulation

Kumar, Mahesh; Sabba, Dharani; Leong, Wei Lin; Boix, Pablo P.; Prabhakar, Rajiv Ramanujam; Baikie, Tom; Shi, Chen; Ding, Hong; Ramesh, R.; Asta, Mark; Gräetzel, Michael; Mhaisalkar, Subodh; Mathews, Nripan

doi:10.1002/adma.201401991

Cited by 1,020 publications

(1,177 citation statements)

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“…Meanwhile, SnF 2 was included in the precursor as an additive, as it is reported to suppress the doped hole density in Sn‐based perovskites 16, 17. To investigate the intercalation of FA and MA cations in our mixed‐cation perovskites, we measured the X‐ray diffraction (XRD) patterns of these perovskite films on ITO/PEDOT:PSS substrates ( Figure 1 a).…”

Section: Resultsmentioning

confidence: 99%

“…For example, SnF 2 , as an additive, has been found to effectively suppress the doped hole density in Sn‐based perovskites and improve device stability and reproducibility 16, 17. The use of dimethyl sulfoxide (DMSO) as the precursor solvent has proven to be crucial in acquiring homogeneous films, as it forms a SnI 2 ·3DMSO intermediate phase that retards the rapid crystallization of Sn‐based perovskites 18.…”

Section: Introductionmentioning

confidence: 99%

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Mixed‐Organic‐Cation Tin Iodide for Lead‐Free Perovskite Solar Cells with an Efficiency of 8.12%

et al. 2017

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In this work, a fully tin‐based, mixed‐organic‐cation perovskite absorber (FA)x(MA)1− xSnI3 (FA = NH2CH = NH2 +, MA = CH3NH3 +) for lead‐free perovskite solar cells (PSCs) with inverted structure is presented. By optimizing the ratio of FA and MA cations, a maximum power conversion efficiency of 8.12% is achieved for the (FA)0.75(MA)0.25SnI3‐based device along with a high open‐circuit voltage of 0.61 V, which originates from improved perovskite film morphology and inhibits recombination process in the device. The cation‐mixing approach proves to be a facile method for the efficiency enhancement of tin‐based PSCs.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mixed‐Organic‐Cation Tin Iodide for Lead‐Free Perovskite Solar Cells with an Efficiency of 8.12%

et al. 2017

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“…The magic effect of SnF 2 attracted researcher to investigate its working mechanism. In 2014, Kumar et al69 demonstrated for the first time that the introduction of SnF 2 into CsSnI 3 can reduce Sn vacancies and background carrier densities. Therefore, high J SC of more than 22 mA cm −2 and a PCE of 2.02% were achieved in contrast to the nonfunctioning devices without SnF 2 .…”

Section: Lead‐free Halide Hybrid Perovskite and Related Absorbersmentioning

confidence: 99%

“…The conventional one‐step film deposition method of tin perovskites often engenders randomly oriented film growth accompanied by forming large crystals platelets and poor surface coverage with micron‐sized pinholes 46. The flawed films further led to the poorly performing devices 69. Moreover, due to the reaction kinetics between organic/inorganic halide and tin halide salts is faster than its lead analogs,19, 46, 156 the control of tin perovskite crystallization during the deposition process is more challenging.…”

Section: Lead‐free Halide Hybrid Perovskite and Related Absorbersmentioning

confidence: 99%

Lead‐Free Hybrid Perovskite Absorbers for Viable Application: Can We Eat the Cake and Have It too?

2017

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Many years since the booming of research on perovskite solar cells (PSCs), the hybrid perovskite materials developed for photovoltaic application form three main categories since 2009: (i) high‐performance unstable lead‐containing perovskites, (ii) low‐performance lead‐free perovskites, and (iii) moderate performance and stable lead‐containing perovskites. The search for alternative materials to replace lead leads to the second group of perovskite materials. To date, a number of these compounds have been synthesized and applied in photovoltaic devices. Here, lead‐free hybrid light absorbers used in PV devices are focused and their recent developments in related solar cell applications are reviewed comprehensively. In the first part, group 14 metals (Sn and Ge)‐based perovskites are introduced with more emphasis on the optimization of Sn‐based PSCs. Then concerns on halide hybrids of group 15 metals (Bi and Sb) are raised, which are mainly perovskite derivatives. At the same time, transition metal Cu‐based perovskites are also referred. In the end, an outlook is given on the design strategy of lead‐free halide hybrid absorbers for photovoltaic applications. It is believed that this timely review can represent our unique view of the field and shed some light on the direction of development of such promising materials.

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“…[12,13] In an attempt to improve the PCE, research efforts have been directed towards optimization of the tin-perovskite film morphology, tuning the film composition, use of a reducing agent, and modification of the device structure. [14][15][16][17][18][19][20][21] The main challenges for further improving the PCE lie in preventing the easy formation of Sn vacancies due to their small formation energy and the fast oxidation of divalent Sn 2+ into more stable Sn 4+ . This causes high levels of self-p-doping in Sn-based perovskite films, with consequent severe recombination losses for charge carriers.…”

Section: Doi: 101002/aenm201702019mentioning

confidence: 99%

Highly Reproducible Sn‐Based Hybrid Perovskite Solar Cells with 9% Efficiency

Shao

Liu

Portale

et al. 2017

Advanced Energy Materials

779

778

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The low power conversion efficiency (PCE) of tin‐based hybrid perovskite solar cells (HPSCs) is mainly attributed to the high background carrier density due to a high density of intrinsic defects such as Sn vacancies and oxidized species (Sn4+) that characterize Sn‐based HPSCs. Herein, this study reports on the successful reduction of the background carrier density by more than one order of magnitude by depositing near‐single‐crystalline formamidinium tin iodide (FASnI3) films with the orthorhombic a‐axis in the out‐of‐plane direction. Using these highly crystalline films, obtained by mixing a very small amount (0.08 m) of layered (2D) Sn perovskite with 0.92 m (3D) FASnI3, for the first time a PCE as high as 9.0% in a planar p–i–n device structure is achieved. These devices display negligible hysteresis and light soaking, as they benefit from very low trap‐assisted recombination, low shunt losses, and more efficient charge collection. This represents a 50% improvement in PCE compared to the best reference cell based on a pure FASnI3 film using SnF2 as a reducing agent. Moreover, the 2D/3D‐based HPSCs show considerable improved stability due to the enhanced robustness of the perovskite film compared to the reference cell.

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Lead‐Free Halide Perovskite Solar Cells with High Photocurrents Realized Through Vacancy Modulation

Abstract: Lead free perovskite solar cells based on a CsSnI3 light absorber with a spectral response from 950 nm is demonstrated. The high photocurrents noted in the system are a consequence of SnF2 addition which reduces defect concentrations and hence the background charge carrier density.

Cited by 1,020 publications

References 33 publications

Mixed‐Organic‐Cation Tin Iodide for Lead‐Free Perovskite Solar Cells with an Efficiency of 8.12%

Mixed‐Organic‐Cation Tin Iodide for Lead‐Free Perovskite Solar Cells with an Efficiency of 8.12%

Lead‐Free Hybrid Perovskite Absorbers for Viable Application: Can We Eat the Cake and Have It too?

Highly Reproducible Sn‐Based Hybrid Perovskite Solar Cells with 9% Efficiency

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