| 1. |
- Bai, Sai, et al.
(author)
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Planar perovskite solar cells with long-term stability using ionic liquid additives
- 2019
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In: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 571:7764, s. 245-250
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Journal article (peer-reviewed)abstract
- Solar cells based on metal halide perovskites are one of the most promising photovoltaic technologies(1-4). Over the past few years, the long-term operational stability of such devices has been greatly improved by tuning the composition of the perovskites(5-9), optimizing the interfaces within the device structures(10-13), and using new encapsulation techniques(14,15). However, further improvements are required in order to deliver a longer-lasting technology. Ion migration in the perovskite active layer-especially under illumination and heat-is arguably the most difficult aspect to mitigate(16-18). Here we incorporate ionic liquids into the perovskite film and thence into positive-intrinsic-negative photovoltaic devices, increasing the device efficiency and markedly improving the long-term device stability. Specifically, we observe a degradation in performance of only around five per cent for the most stable encapsulated device under continuous simulated full-spectrum sunlight for more than 1,800 hours at 70 to 75 degrees Celsius, and estimate that the time required for the device to drop to eighty per cent of its peak performance is about 5,200 hours. Our demonstration of long-term operational, stable solar cells under intense conditions is a key step towards a reliable perovskite photovoltaic technology.
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| 2. |
- Bai, Sai, et al.
(author)
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Reproducible Planar Heterojunction Solar Cells Based on One-Step Solution-Processed Methylammonium Lead Halide Perovskites
- 2017
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In: Chemistry of Materials. - : AMER CHEMICAL SOC. - 0897-4756 .- 1520-5002. ; 29:1, s. 462-473
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Journal article (peer-reviewed)abstract
- Metal halide perovskites have been demonstrated as one of the most promising materials for low-cost and high-performance photovoltaic applications. However, due to the susceptible crystallization process of perovskite films on planar substrates and the high sensitivity of the physical and optoelectronic nature of the internal interfaces within the devices, researchers in different laboratories still experience poor reproducibility in fabricating efficient perovskite solar cells with planar heterojunction device structures. In this method paper, we present detailed information on the reagents, equipment, and procedures for the fabrication of planar perovskite solar cells in both "regular" n-i-p and "inverted" p-i-n architectures based on one-step solution-processed methylammonium lead triiodide (MAPbI(3)) perovskite films. We discuss key parameters affecting the crystallization of perovskite and the device interfaces. This method paper will provide a guideline for the reproducible fabrication of planar heterojunction solar cells based on MAPbI3 perovskite films. We believe that the shared experience on MA-based perovskite films and planar solar cells will be also useful for the optimization process of perovskites with varied compositions, and other emerging perovskite-based optoelectronic devices.
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| 3. |
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| 4. |
- Conings, Bert, et al.
(author)
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Getting rid of anti-solvents: gas quenching for high performance perovskite solar cells
- 2018
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In: 2018 IEEE 7TH WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION (WCPEC) (A JOINT CONFERENCE OF 45TH IEEE PVSC, 28TH PVSEC and 34TH EU PVSEC). - : IEEE. - 9781538685297 ; , s. 1724-1729
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Conference paper (peer-reviewed)abstract
- As the field of perovskite optoelectronics developed, a plethora of strategies has arisen to control their electronic and morphological characteristics for the purpose of producing high efficiency devices. Unfortunately, despite this wealth of deposition approaches, the community experiences a great deal of irreproducibility between different laboratories, batches and preparation methods. Aiming to address this issue, we developed a simple deposition method based on gas quenching that yields smooth films for a wide range of perovskite compositions, in single, double, triple and quadruple cation varieties, and produces planar heterojunction devices with competitive efficiencies, so far up to 20%.
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| 5. |
- Lin, Yen-Hung, et al.
(author)
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A piperidinium salt stabilizes efficient metal-halide perovskite solar cells
- 2020
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In: Science. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075 .- 1095-9203. ; 369:6499, s. 96-
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Journal article (peer-reviewed)abstract
- Longevity has been a long-standing concern for hybrid perovskite photovoltaics. We demonstrate high-resilience positive-intrinsic-negative perovskite solar cells by incorporating a piperidinium-based ionic compound into the formamidinium-cesium lead-trihalide perovskite absorber. With the bandgap tuned to be well suited for perovskite-on-silicon tandem cells, this piperidinium additive enhances the open-circuit voltage and cell efficiency. This additive also retards compositional segregation into impurity phases and pinhole formation in the perovskite absorber layer during aggressive aging. Under full-spectrum simulated sunlight in ambient atmosphere, our unencapsulated and encapsulated cells retain 80 and 95% of their peak and post-burn-in efficiencies for 1010 and 1200 hours at 60 degrees and 85 degrees C, respectively. Our analysis reveals detailed degradation routes that contribute to the failure of aged cells.
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| 6. |
- Liu, Jiewei, et al.
(author)
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Identification and Mitigation of a Critical Interfacial Instability in Perovskite Solar Cells Employing Copper Thiocyanate Hole-Transporter
- 2016
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In: ADVANCED MATERIALS INTERFACES. - : WILEY. - 2196-7350. ; 3:22
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Journal article (peer-reviewed)abstract
- Metal halide perovskites have emerged as one of the most promising materials for photovoltaics (PVs), with power conversion efficiency of over 22% already demonstrated. In order to compete with traditional crystalline silicon PV, cost and stability are equally important issues that need to be considered besides efficiency. Copper thiocyanate (CuSCN) is an interesting candidate to be used as an inexpensive, thermally stable p-type charge conducting material in perovskite solar cells. Here, we report 13% efficient perovskite solar cells employing CuSCN as the hole-transport material. We compare the stability of cells employing CuSCN with those employing the archetypical organic hole-transporter 2,2 ,7,7 -Tetrakis (N,N-di-p-methoxyphenyl-amine) 9,9-Spirobifluorene (Spiro-OMeTAD), under elevated temperature in ambient atmosphere. Surprisingly, we find that the devices employing CuSCN degrade faster under elevated temperatures than the devices employing SpiroOMeTAD. We discover that an interfacial degradation mechanism occurs at the heterojunction between the perovskite absorber and the CuSCN, even in a dry nitrogen atmosphere, identifying the presence of a critical instability. Interestingly, with the additional coating of the completed cells with a thin film of insulating poly(methyl methacrylate) (PMMA), functioning as a rudimentary "on-cell" encapsulation, we significantly alleviate this issue and deliver efficient perovskite solar cells which survive for more than 1000 hours at 85 degrees C in air with only 25% degradation in performance. Beyond identifying a critical area to address in order to enable CuSCN to be useful for long term operation in perovskite solar cells, our findings indicate that the role of the "encapsulant" is to both keep the environment out, and keep degradation products within the cell.
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