Unveiling the Critical Role of Oxidants and Additives in Doped Spiro-OMeTAD toward Stable and Efficient Perovskite Solar Cells

Zhu, Guojie; Yang, Li; Zhang, Cuiping; Du, Guozheng; Fan, Naiyuan; Luo, Zhide; Zhang, Xiaoli; Zhang, Jinbao

doi:10.1021/acsaem.1c04097

Cited by 33 publications

(31 citation statements)

References 39 publications

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“…The conductivity of these films was examined by recording the I−V curves of devices with the configuration FTO/CsBi 3−x Sb x I 10 (Figure 2d). Clearly, CsBi 2.7 Sb 0.3 I 10 showed a much higher conductivity compared to CBI, indicating faster charge separation in the CsBi 2.7 Sb 0.3 I 10 film, 30,31 which will be beneficial for increasing the charge collection efficiency in devices. 32 To examine the changes of the surface morphology of perovskite films, scanning electron microscopy (SEM) was performed for CBI and Sb-doped films.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Antimony Doping of CsBi₃I₁₀ for Tailoring the Film Morphology and Defects toward Efficient Lead-Free Thin-Film Solar Cells

Yang

Deng

et al. 2022

ACS Appl. Energy Mater.

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The CsBi3I10 (CBI) semiconductor as a light absorber emerges as a promising alternative to lead-based perovskites owing to its low toxicity, good stability, and satisfying physical properties. However, CBI exhibits an uncontrollable crystallization process, poor film morphology, high defect density, and short carrier lifetime, which lead to inferior optoelectronic properties, limiting its practical application in solar cell devices. Here, the Sb doping strategy is successfully developed for CBI films by a one-step antisolvent-free fabrication method. It is found that Sb incorporation in binary CsBi3–x Sb x I10 can modulate the crystallization kinetics and optimize the film quality. As a result, polycrystalline films with high density and few pinholes are obtained to enable the enhancement of light absorbance, reduction of defects, suppression of nonradiative recombination, and increase of surface hydrophobicity. The solar cells based on the CsBi2.7Sb0.3I10 film show a remarkably improved power conversion efficiency of 0.82% compared to that of pristine CBI (0.22%), which is among the highest reported efficiencies for CBI-based thin-film solar cells. Moreover, unencapsulated devices based on Sb-doped CBI exhibit outstanding environmental stability and moisture tolerance. This work not only offers insights into understanding the binary Bi-based materials but also provides a new way to fabricate efficient and stable Bi-based solar cells.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Antimony Doping of CsBi₃I₁₀ for Tailoring the Film Morphology and Defects toward Efficient Lead-Free Thin-Film Solar Cells

Yang

Deng

et al. 2022

ACS Appl. Energy Mater.

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“…[20][21][22] Indeed, Seo et al demonstrated that replacing the Li + in favor of Zn + improves the stability of the spiro-OMeTAD when illuminated over a period of 600 h. [21] Similarly, copper salts including cuprous thiocyanate, cuprous iodide, FK102 and FK209 amongst other copper (II) salts, have been frequently used on their own or as a co-dopant additive with LiTFSI to oxidize spiro-OMeTAD. [6,23,24] Recently, Zhu et al identified that by using FK209, arguably the most common copper-based additive, as a sole p-type dopant, the stability of spiro-OMeTAD could be improved via enhancing the morphology and hydrophobicity. This observation has been frequently reported in copper-based spiro-OMeTAD dopants.…”

Section: Introductionmentioning

confidence: 99%

“…This observation has been frequently reported in copper-based spiro-OMeTAD dopants. [6,23,24] However, for optimal hole conduction and subsequent device performance, LiTFSI is required as a co-dopant. In this context, developing strategies that can be easily integrated to improve the long-term stability of the LiTFSI-doped spiro-OMeTAD devices whilst also maintaining high PCEs is essential and a practical choice.…”

Section: Introductionmentioning

confidence: 99%

A Multifaceted Ferrocene Interlayer for Highly Stable and Efficient Lithium Doped Spiro‐OMeTAD‐based Perovskite Solar Cells

Webb

Liu

Westbrook

et al. 2022

Advanced Energy Materials

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hole mobilities within the HTL of up to 1.6 × 10 -3 cm 2 V -1 s -1 . [4] However, the use of such highly hygroscopic lithium salts has been shown to dramatically accelerate the degradation of PSCs. [5][6][7][8] Previous works have identified that upon doping with LiTFSI, lithium ions can readily become mobile and diffuse within the perovskite layer, forming hygroscopic LiX salts (where Xis a halide) which in turn rapidly degrade the perovskite. [5,[9][10][11][12][13][14] Wang et al demonstrated that following evaporation of tert-butylpyridine (tBP), a common spiro-OMeTAD additive, LiTFSI begins to form hygroscopic aggregates which hydrate the perovskite/spiro-OMeTAD interface degrading the perovskite over a period of < 1000 hours. [8] Furthermore, it has also been shown that tBP is, by itself, insufficient to prevent the migration of lithium ions. [7] To this extent, Kim et al. recently revealed that the migration of Li + is critical in the degradation of spiro-OMeTAD-based devices and is accelerated at higher temperatures, leading to the rapid degradation of the perovskite. [7] For these combined reasons spiro-OMeTAD-based PSCs consistently fall short of the practical requirements for the commercialization of solar cells. Indeed, the poor stability of LiTFSI doped spiro-OMeTAD as an HTL has become such a problem that many leading studies using the architecture replace the HTL with a more stable, yet lower efficiency, alternative or emit reporting stability entirely. [6,15] Consequently, addressing the impact of lithium on device stability is one of the biggest challenges facing the highest efficiency PSCs.As of writing, two principal strategies have emerged within the literature for improving the stability of n-i-p PSCs, namely (i) searching for new less destructive dopants or (ii) replacing spiro-OMeTAD in favor of alternative stable HTLs such as poly(triarylamine) (PTAA), poly(3-hexathiophene) (P3HT) or a range of novel molecular transporting materials (Table S1, Supporting Information). [5,[16][17][18] While these candidates can yield improvements in the long-term stability, the PCEs of resultant devices remain inferior to the spiro-OMeTAD counterparts. This performance gap has led to a trade-off between efficiency and stability in PSCs. More recently the formation of a blocking layer between the lithium doped spiro-OMeTAD HTL and the perovskite has been suggested using either graphene or flower-like MoS 2 . [11,19] Similar to the previous approaches, devices prepared using a blocking layer have yet to match the high efficiencies achieved using the conventional spiro-OMeTAD architecture, reaching up to 20.18% in devices prepared with MoS 2 . Furthermore, by blocking the Li + at the interface, the mechanism by which hygroscopic agregates are formed is not avoided. This challenge, therefore, requires new strategies that target the Li + ions within the HTL itself, preventing the accumulation of Li + at the interface and subsequent degradation. Very recently, several studies have sought to replace the Li + metal ...

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“…Longer τ n means a slower recombination process, which is beneficial for a higher charge collection efficiency. [ 58 ] The longer τ n for the devices with KSCN‐PEO compared with the other devices could be mostly associated with the high‐quality perovskite film in terms of crystallinity, conductivity, uniformity, and defect density. To further understand the charge recombination mechanism, we carried out V oc versus light intensity measurements.…”

Section: Resultsmentioning

confidence: 99%

A Core@Dual–Shell Nanostructured SnO₂to Modulate the Buried Interfaces Toward Stable Perovskite Solar Cells With Minimized Energy Losses

Wei

Deng

Yang

et al. 2022

Advanced Energy Materials

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Investigation and optimization of the buried interfaces are crucial for further improving the efficiency and stability of perovskite solar cells (PSCs). In this work, a general route to modify the interfaces of electron conductor is strategically developed via introducing a well‐designed core@dual–shell structure based on SnO2 nanoparticles grafted by potassium thiocyanate (KSCN) and polyethylene oxide (PEO). This graded bimolecular strategy is desired as it efficiently decouples the processes of defect healing and crystallization engineering. Synergistic effects of KSCN and PEO lead to superior structural uniformity at the buried interfaces, enhanced charge collection, as well as the suppressed carrier recombination. Consequently, a significant increase of efficiency from 20.0% to 23.01% is achieved, accompanied by a remarkable open‐circuit voltage of 1.19 V and extremely low energy losses down to 0.4 eV. Moreover, this interfacial configuration enables the unencapsulated devices to have greatly improved performance longevity by retaining 87% of initial power after 5112 h storage in air, as well as strong mechanical endurance by maintaining over 80% of initial efficiency after 4700 bending cycles at a curvature radius of 5 mm for flexible devices. This work offers an effective and generally applicable approach for engineering the nanostructured interface to realize stable and efficient PSCs.

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Unveiling the Critical Role of Oxidants and Additives in Doped Spiro-OMeTAD toward Stable and Efficient Perovskite Solar Cells

Cited by 33 publications

References 39 publications

Antimony Doping of CsBi₃I₁₀ for Tailoring the Film Morphology and Defects toward Efficient Lead-Free Thin-Film Solar Cells

Antimony Doping of CsBi₃I₁₀ for Tailoring the Film Morphology and Defects toward Efficient Lead-Free Thin-Film Solar Cells

A Multifaceted Ferrocene Interlayer for Highly Stable and Efficient Lithium Doped Spiro‐OMeTAD‐based Perovskite Solar Cells

A Core@Dual–Shell Nanostructured SnO₂to Modulate the Buried Interfaces Toward Stable Perovskite Solar Cells With Minimized Energy Losses

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Unveiling the Critical Role of Oxidants and Additives in Doped Spiro-OMeTAD toward Stable and Efficient Perovskite Solar Cells

Cited by 33 publications

References 39 publications

Antimony Doping of CsBi3I10 for Tailoring the Film Morphology and Defects toward Efficient Lead-Free Thin-Film Solar Cells

Antimony Doping of CsBi3I10 for Tailoring the Film Morphology and Defects toward Efficient Lead-Free Thin-Film Solar Cells

A Multifaceted Ferrocene Interlayer for Highly Stable and Efficient Lithium Doped Spiro‐OMeTAD‐based Perovskite Solar Cells

A Core@Dual–Shell Nanostructured SnO2to Modulate the Buried Interfaces Toward Stable Perovskite Solar Cells With Minimized Energy Losses

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Antimony Doping of CsBi₃I₁₀ for Tailoring the Film Morphology and Defects toward Efficient Lead-Free Thin-Film Solar Cells

Antimony Doping of CsBi₃I₁₀ for Tailoring the Film Morphology and Defects toward Efficient Lead-Free Thin-Film Solar Cells

A Core@Dual–Shell Nanostructured SnO₂to Modulate the Buried Interfaces Toward Stable Perovskite Solar Cells With Minimized Energy Losses