| 1. |
- Jeong, Jaeki, et al.
(author)
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Pseudo-halide anion engineering for α-FAPbI3 perovskite solar cells
- 2021
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In: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 592:7854, s. 381-385
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Journal article (peer-reviewed)abstract
- Metal halide perovskites of the general formula ABX(3)-where A is a monovalent cation such as caesium, methylammonium or formamidinium; B is divalent lead, tin or germanium; and X is a halide anion-have shown great potential as light harvesters for thin-film photovoltaics(1-5). Among a large number of compositions investigated, the cubic a-phase of formamidinium lead triiodide (FAPbI(3)) hasemerged as the most promising semiconductor for highly efficient and stable perovskite solar cells(6-9), and maximizing the performance of this material in such devices is of vital importance for the perovskite researchcommunity. Here we introduce an anion engineering concept that uses the pseudo-halide anion formate (HCOO-) to suppress anion-vacancy defects that are present at grain boundaries and at the surface of the perovskite films and to augment the crystallinity of the films. Theresulting solar cell devices attain a power conversion efficiency of 25.6 per cent (certified 25.2 per cent), have long-term operational stability (450 hours) and show intense electroluminescence with external quantum efficiencies of more than 10 per cent. Our findings provide a direct route to eliminate the most abundant and deleterious lattice defects present in metal halide perovskites, providing a facile access to solution-processable films with improved optoelectronic performance.
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| 2. |
- Kajal, Sandeep, et al.
(author)
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Coordination modulated passivation for stable organic-inorganic perovskite solar cells
- 2023
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In: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 451
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Journal article (peer-reviewed)abstract
- Despite the recent exceptional rise in power conversion efficiency of perovskite solar cells (PSCs), surface defects and ion migration related instability are still present in PSCs. The chain length and binding energy of the passivation material play important roles in defect passivation, ion migration, moisture stability, and device-performance improvement. We synthesized three sulfonated ammonium compounds and investigated the ef-fect of post-passivation with these compounds on ion-migration and stability. New materials with high binding energy include octylamine (OA) functionalized with sulfanilic acid (OAS), p-toluenesulfonic acid (OAT), and camphorsulfonic acid (OAC). The passivation improves power conversion efficiency (PCE) from 21.06% for the control to 24.37% for the devices treated with OAC. The champion device's hysteresis index decreased to 0.01 compared to 0.11 for the control device, which is the lowest reported so far. Furthermore, the passivated perovskite films retain over 85% of their initial PCE under 60% relative humidity for 1,600 h, and the device with OAC maintains over 90% of its initial operational long-term device stability without encapsulation for 600 h under 1 sun-illumination.
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| 3. |
- Kim, Minjin, et al.
(author)
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Conformal quantum dot-SnO2 layers as electron transporters for efficient perovskite solar cells
- 2022
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375:6578, s. 302-306
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Journal article (peer-reviewed)abstract
- Improvements to perovskite solar cells (PSCs) have focused on increasing their power conversion efficiency (PCE) and operational stability and maintaining high performance upon scale-up to module sizes. We report that replacing the commonly used mesoporous-titanium dioxide electron transport layer (ETL) with a thin layer of polyacrylic acid-stabilized tin(IV) oxide quantum dots (paa-QD-SnO2) on the compact-titanium dioxide enhanced light capture and largely suppressed nonradiative recombination at the ETL-perovskite interface. The use of paa-QD-SnO2 as electron-selective contact enabled PSCs (0.08 square centimeters) with a PCE of 25.7% (certified 25.4%) and high operational stability and facilitated the scale-up of the PSCs to larger areas. PCEs of 23.3, 21.7, and 20.6% were achieved for PSCs with active areas of 1, 20, and 64 square centimeters, respectively.
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| 4. |
- Suo, Jiajia, et al.
(author)
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Interfacial engineering from material to solvent : A mechanistic understanding on stabilizing alpha-formamidinium lead triiodide perovskite photovoltaics
- 2022
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In: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 94
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Journal article (peer-reviewed)abstract
- Formamidinium lead triiodide (FAPbI3) has recently been considered as the most promising candidate to achieve highly efficient perovskite solar cells (PSCs). Excitingly, the state-of-the-art highest efficiency of FAPbI3 based PSCs have reached over 25%. However, their device stability still lags behind other compositions of mixed-cation and mixed-halide perovskites. Interfacial engineering is a very powerful method to address this issue and passivation agents have been intensively developed, however there is a lack of in-depth understanding regarding the solvent selection during post-treatment. Here, we employed cyclohexylmethylammonium iodide (CMAI) as passivation agent, which is investigated using either isopropanol (IPA) or chloroform (CF) as carrier mediator to study the solvent influence on the stabilization of FAPbI3. We observed a suppressed-defect perovskite surface toward distinguished composition with 2D CMA2PbI4 domain and CMAI domain induced by IPA and CF, respectively. Remarkably, post-treatment with solution of CMAI in CF creates a strain-free environment on the perovskite surface, leading to an improved efficiency of approaching 24% and concurrently an extraordinarily stable alpha-phase FAPbI3 PSCs under operation condition, retaining 95% of its initial efficiency after 1050-hour aging. Our resulting device stability is one of the most stable FAPbI3 based PSCs reported in literature.
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