Cesium methylammonium lead iodide (Cs
Hybrid organic–inorganic perovskites (HOIPs) such as methylammonium lead iodide (MAPbI3) are promising candidates for use in photovoltaic cells and other semiconductor applications, but their limited chemical stability poses obstacles to their widespread use.
- Award ID(s):
- 1729297
- PAR ID:
- 10482482
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Journal of Physics: Energy
- Volume:
- 6
- Issue:
- 1
- ISSN:
- 2515-7655
- Format(s):
- Medium: X Size: Article No. 015015
- Size(s):
- Article No. 015015
- Sponsoring Org:
- National Science Foundation
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Abstract x MA1−x PbI3) nanocrystals were obtained with a wide range of A‐site Cs‐MA compositions by post‐synthetic, room temperature cation exchange between CsPbI3nanocrystals and MAPbI3nanocrystals. The alloyed Csx MA1−x PbI3nanocrystals retain their photoactive perovskite phase with incorporated Cs content,x , as high as 0.74 and the expected composition‐tunable photoluminescence (PL). Excess methylammonium oleate from the reaction mixture in the MAPbI3nanocrystal dispersions was necessary to obtain fast Cs‐MA cation exchange. The phase transformation and degradation kinetics of films of Csx MA1−x PbI3nanocrystals were measured and modeled using an Avrami expression. The transformation kinetics were significantly slower than those of the parent CsPbI3and MAPbI3nanocrystals, with Avrami rate constants,k , at least an order of magnitude smaller. These results affirm that A‐site cation alloying is a promising strategy for stabilizing iodide‐based perovskites. -
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Abstract Cesium methylammonium lead iodide (Cs
x MA1−x PbI3) nanocrystals were obtained with a wide range of A‐site Cs‐MA compositions by post‐synthetic, room temperature cation exchange between CsPbI3nanocrystals and MAPbI3nanocrystals. The alloyed Csx MA1−x PbI3nanocrystals retain their photoactive perovskite phase with incorporated Cs content,x , as high as 0.74 and the expected composition‐tunable photoluminescence (PL). Excess methylammonium oleate from the reaction mixture in the MAPbI3nanocrystal dispersions was necessary to obtain fast Cs‐MA cation exchange. The phase transformation and degradation kinetics of films of Csx MA1−x PbI3nanocrystals were measured and modeled using an Avrami expression. The transformation kinetics were significantly slower than those of the parent CsPbI3and MAPbI3nanocrystals, with Avrami rate constants,k , at least an order of magnitude smaller. These results affirm that A‐site cation alloying is a promising strategy for stabilizing iodide‐based perovskites. -
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The current understanding of the crystallization, morphology evolution, and phase stability of wide‐bandgap hybrid perovskite thin films is very limited, as much of the community's focus is on lower bandgap systems. Herein, the crystallization behavior and film formation of a wide and tunable bandgap MAPbBr3
− x Clx system are investigated, and its formation and phase stability are contrasted to the classical MAPbI3− x Brx case. A multiprobe in situ characterization approach consisting of synchrotron‐based grazing incidence wide‐angle X‐ray scattering and laboratory‐based time‐resolved UV–Vis absorbance measurements is utilized to show that all wide‐bandgap perovskite compositions of MAPbBr3− x Clx studied (0 <x < 3) crystallize the same way: the perovskite phase forms directly from the colloidal sol state and forms a solid film in the cubic structure. This results in significantly improved alloying and phase stability of these compounds compared with MAPbI3− x Brx systems. The phase transformation pathway is direct and excludes solvated phases, in contrast to methylammonium lead iodide (MAPbI3). The films benefit from antisolvent dripping to overcome the formation of discontinuous layers and enable device integration. Pin‐hole‐free MAPbBr3− x Clx hybrid perovskite thin films with a tunable bandgap are, thus, integrated into working single‐junction solar cell devices and achieve a tunable open‐circuit voltage as high as 1.6 V. -
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Abstract Organic–inorganic halide perovskites are intrinsically unstable when exposed to moisture and/or light. Additionally, the presence of lead in many perovskites raises toxicity concerns. Herein, a thin film of barium zirconium sulfide (BaZrS3), a lead‐free chalcogenide perovskite, is reported. Photoluminescence and X‐ray diffraction measurements show that BaZrS3is far more stable than methylammonium lead iodide (MAPbI3) in moist environments. Moisture‐ and light‐induced degradations in BaZrS3and MAPbI3are compared by using simulations and calculations based on density functional theory. The simulations reveal drastically slower degradation in BaZrS3due to two factors—weak interaction with water and very low rates of ion migration. BaZrS3photodetecting devices with photoresponsivity of ≈46.5 mA W−1are also reported. The devices retain ≈60% of their initial photoresponse after 4 weeks under ambient conditions. Similar MAPbI3devices degrade rapidly and show a ≈95% decrease in photoresponsivity in just 4 days. The findings establish the superior stability of BaZrS3and strengthen the case for its use in optoelectronics. New possibilities for thermoelectric energy conversion using these materials are also demonstrated.
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Abstract Surface passivation of perovskite solar cells (PSCs) using a low‐cost industrial organic pigment quinacridone (QA) is presented. The procedure involves solution processing a soluble derivative of QA,
N ,N ‐bis(tert‐butyloxycarbonyl)‐quinacridone (TBOC‐QA), followed by thermal annealing to convert TBOC‐QA into insoluble QA. With halide perovskite thin films coated by QA, PSCs based on methylammonium lead iodide (MAPbI3) showed significantly improved performance with remarkable stability. A PCE of 21.1 % was achieved, which is much higher than 18.9 % recorded for the unmodified devices. The QA coating with exceptional insolubility and hydrophobicity also led to greatly enhanced contact angle from 35.6° for the pristine MAPbI3thin films to 77.2° for QA coated MAPbI3thin films. The stability of QA passivated MAPbI3perovskite thin films and PSCs were significantly enhanced, retaining about 90 % of the initial efficiencies after more than 1000 hours storage under ambient conditions.
