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Ruddlesden–Popper perovskites (RPPs) are promising materials for optoelectronic devices. While iodide‐based RPPs are well‐studied, the crystallization of mixed‐halide RPPs remains less explored. Understanding the factors affecting their formation and crystallization are vital for optimizing morphology, phase purity, and orientation, which directly impact device performance. Here, we investigate the crystallization and properties of mixed‐halide RPPs (PEA)2FAn−1Pbn(Br1/3I2/3)3n + 1(PEA = C6H5(CH2)2NH3+and FA = CH(NH2)2+) (n = 1, 5, 10) using DMSO ((CH3)2SO) or NMP (OC4H6NCH3) as cosolvents and MACl (MA = CH3NH3+) as an additive. For the first time, the presence of planar defects in RPPs is directly observed by in situ grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) and confirmed through the simulation of the patterns that matched the experimental. GIWAXS data also reveals that DMSO promotes higher crystallinity and vertical orientation, while MACl enhances crystal quality but increases halide segregation, shown here by nano X‐ray fluorescence (nano‐XRF) experiments. For low‐n RPPs, orientation is crucial for solar cell efficiency, but its impact decreases with increasing n. Our findings provide insights into optimizing mixed‐halide RPPs, guiding strategies to improve crystallization, phase control, and orientation for better performance not only in solar cells but also in other potential optoelectronic devices.
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Optimization of surface passivation for suppressing leakage current in GaSb PIN devices
The suppression of leakage current via surface passivation plays a critical role for GaSb‐based optoelectronic devices. In this Letter the authors carefully optimise the sulfur passivation parameters for improving the performance of GaSb p–i–n devices. Two competing processes are evaluated during the sulfur passivation process: the hydrolysis of HS–ions that aide surface passivation and the re‐oxidation, respectively. Upon the optimisation of sulfur passivation parameters and subsequent encapsulation with atomic layer deposition Al2O3, the surface resistivity significantly increased from 4.3 kΩ.cm to 28.6 kΩ.cm, leading to a 19.1 times drop in dark current at room temperature for the GaSb p–i–n structure. This Letter provides a repeatable and stable passivation approach for improving the optoelectronic performance of GaSb‐based devices.
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- Award ID(s):
- 1810507
- PAR ID:
- 10570603
- Publisher / Repository:
- DOI PREFIX: 10.1049
- Date Published:
- Journal Name:
- Electronics Letters
- Volume:
- 56
- Issue:
- 25
- ISSN:
- 0013-5194
- Format(s):
- Medium: X Size: p. 1420-1423
- Size(s):
- p. 1420-1423
- Sponsoring Org:
- National Science Foundation
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