Abstract:Grain boundaries in Cu 2 ZnSn(S x Se 1-x ) 4 (CZTSSe) thin films act as a defect that reduces the mobility of the charges. Hence one way to improve the performance of these thin film solar cells is to increase the grain size in the films. Most of the synthesis methods published so far for CZTSSe colloidal nanoparticles can achieve a general size distribution range from 5-20 nm. This is where the particle size will saturate for most recipes used today. The assumption is that uniform size distribution is good fo… Show more
“…We simply described the crystal growth mechanism by applying the LaMer model (Figure S7b, Supporting Information). In the fast A‐NCP process for OSN film formation, the rapid co‐evaporation of the solvents by volatile nonpolar CF induces 1) the simultaneous nucleation at most nucleation sites, 2) a short nucleation period, which induces uniform reactant reaction, to form small and uniform nanograins, 3) a short‐time and instantaneous crystal growth that forms the small grains by the crystallographically misoriented faces related to grain boundaries, 4) a rapid consumption of limited precursor concentration, and 5) the instant rinsing of DMSO, the precursor diffusion medium. Therefore, fast A‐NCP effectively causes the crystal growth to cease before secondary crystal growth by Ostwald ripening.…”
Section: Resultsmentioning
confidence: 99%
“…However, the TPBI molecules inside the quasi‐films are gradually rinsed away during A‐NCP so that some portion of them cannot stay at grain boundaries and thus they do not have a uniform additive distribution throughout the film. On the other hand, fast A‐NCP can effectively confine the additives in MAPbBr 3 :TPBI quasi‐film by instant DMSO rinsing for fast crystallization (Figure S7, Supporting Information) …”
Making small nanograins in polycrystalline organic-inorganic halide perovskite (OIHP) films is critical to improving the luminescent efficiency in perovskite light-emitting diodes (PeLEDs). 3D polycrystalline OIHPs have fundamental limitations related to exciton binding energy and exciton diffusion length. At the same time, passivating the defects at the grain boundaries is also critical when the grain size becomes smaller. Molecular additives can be incorporated to shield the nanograins to suppress defects at grain boundaries; however, unevenly distributed molecular additives can cause imbalanced charge distribution and inefficient local defect passivation in polycrystalline OIHP films. Here, a kinetically controlled polycrystalline organic-shielded nanograin (OSN) film with a uniformly distributed organic semiconducting additive (2,2′,2′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1-Hbenzimidazole), TPBI) is developed mimicking core-shell nanoparticles. The OSN film causes improved photophysical and electroluminescent properties with improved light out-coupling by possessing a low refractive index. Finally, highly improved electroluminescent efficiencies of 21.81% ph el −1 and 87.35 cd A −1 are achieved with a half-sphere lens and four-time increased half-lifetime in polycrystalline PeLEDs. This strategy to make homogeneous, defect-healed polycrystalline core-shell-mimicked nanograin film with better optical out-coupling will provide a simple and efficient way to make highly efficient perovskite polycrystal films and their optoelectronics devices.
“…We simply described the crystal growth mechanism by applying the LaMer model (Figure S7b, Supporting Information). In the fast A‐NCP process for OSN film formation, the rapid co‐evaporation of the solvents by volatile nonpolar CF induces 1) the simultaneous nucleation at most nucleation sites, 2) a short nucleation period, which induces uniform reactant reaction, to form small and uniform nanograins, 3) a short‐time and instantaneous crystal growth that forms the small grains by the crystallographically misoriented faces related to grain boundaries, 4) a rapid consumption of limited precursor concentration, and 5) the instant rinsing of DMSO, the precursor diffusion medium. Therefore, fast A‐NCP effectively causes the crystal growth to cease before secondary crystal growth by Ostwald ripening.…”
Section: Resultsmentioning
confidence: 99%
“…However, the TPBI molecules inside the quasi‐films are gradually rinsed away during A‐NCP so that some portion of them cannot stay at grain boundaries and thus they do not have a uniform additive distribution throughout the film. On the other hand, fast A‐NCP can effectively confine the additives in MAPbBr 3 :TPBI quasi‐film by instant DMSO rinsing for fast crystallization (Figure S7, Supporting Information) …”
Making small nanograins in polycrystalline organic-inorganic halide perovskite (OIHP) films is critical to improving the luminescent efficiency in perovskite light-emitting diodes (PeLEDs). 3D polycrystalline OIHPs have fundamental limitations related to exciton binding energy and exciton diffusion length. At the same time, passivating the defects at the grain boundaries is also critical when the grain size becomes smaller. Molecular additives can be incorporated to shield the nanograins to suppress defects at grain boundaries; however, unevenly distributed molecular additives can cause imbalanced charge distribution and inefficient local defect passivation in polycrystalline OIHP films. Here, a kinetically controlled polycrystalline organic-shielded nanograin (OSN) film with a uniformly distributed organic semiconducting additive (2,2′,2′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1-Hbenzimidazole), TPBI) is developed mimicking core-shell nanoparticles. The OSN film causes improved photophysical and electroluminescent properties with improved light out-coupling by possessing a low refractive index. Finally, highly improved electroluminescent efficiencies of 21.81% ph el −1 and 87.35 cd A −1 are achieved with a half-sphere lens and four-time increased half-lifetime in polycrystalline PeLEDs. This strategy to make homogeneous, defect-healed polycrystalline core-shell-mimicked nanograin film with better optical out-coupling will provide a simple and efficient way to make highly efficient perovskite polycrystal films and their optoelectronics devices.
“…However, these complicated vacuum deposition techniques present difficulties in materials utilisation efficiency and expensive in instruments. Alternatively, solution‐based non‐vacuum deposition techniques, such as electrodeposition [10, 11], metal salt solutions [12–15], nanoparticle inks [16–20] and hydrazine‐based inks [21, 22], do not necessarily require high vacuum facilities. For example, Ilari et al [15] developed a metal salt‐based solution deposition method to synthesis CZTSe photovoltaic cells with an efficiency of 2.76%, in which monoethanolamine and 2‐methoxyethanol were used as organic stabiliser and solvent.…”
Section: Introductionmentioning
confidence: 99%
“…The nanoparticle inks deposition methods involve depositing nanoparticles inks and then selenisation in H 2 Se or Se vapour [23]. The CZTSe nanoparticles were often synthesised by hot injection methods or solvothermal methods, which require complicated Schlenk‐line reaction vessel and intricate post‐processing [19, 24]. The hydrazine‐based inks processing is an attractive way to the synthesis of carbon‐free CZTSSe thin films.…”
“…However, hot-injection synthesis is not appropriate for scaling-up process due to its difficulty in controlling the monomer release. 21 To overcome these drawbacks, researchers have recently instigated the heating up synthesis of CZTS NCs, 22,23 but they used expensive materials, multi-solvents and high reaction temperature > 250 C, which is not suitable for the industrial applications. Therefore, it is necessary to develop a simple and low-cost synthesis method for CZTS NCs to fabricate and commercialize thin lm solar cell devices.…”
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