Recently, perovskite solar cells with high photovoltaic performance based on methylammonium lead halide have attracted great interest due to the superior physical properties of the perovskite optical absorption layer. Here, we investigate the interface carrier transport properties of CHNHPbI film by applying the reported treatment with methylamine gas, to reveal the possible mechanism of high performance perovskite-sensitized solar cell results. It is found that the crystal structure and surface morphology are effectively improved by the room-temperature repair of methylamine atmosphere. The preferred 110 orientation results in a slightly larger band gap, which may contribute to the better energy level matching and carrier transport. Further investigations on relaxation time and electron mobility confirm the significantly enhanced carrier diffusion length, revealing the important role of optimized crystallization on charge transport properties, which may be helpful to seek high-powered perovskite solar cells by optimizing the perovskite synthetic process.
such as the active motility in the perovskite layer and its variety with different fabrication processes. Especially, the relationship between the mobility and photoelectric performance of perovskite solar cells has not been well established so far, which is very important not only for understanding internal mechanisms in perovskite fi lms, but also for designing more effi cient devices.As we all know, the quality of perovskite fi lm, including preferred crystal orientation, morphology, and crystallinity, is an important factor for the overall photovoltaic performance of PSC devices. [9][10][11] For the photovoltaic absorber CH 3 NH 3 PbI 3 , it was shown that the CH 3 NH 3 molecular motion can induce a dynamical bandgap, which prevents the carrier recombination and contributes to excition separation, resulting in the increasing of the conversion efficiency. [ 12 ] The slightly larger grain size and preferred (110) orientation of CH 3 NH 3 PbI 3 were also found to be benefi cial for reducing trap density and increasing the open circuit voltage as well as the fi ll factor. [ 13 ] Besides, the increased grain size and crystallinity in CH 3 NH 3 PbI 3 achieved by solvent annealing could result in signifi cant improvement on material electronic property and the photovoltaic device performance. [ 14 ] Especially by varying the perovskite capping layer thickness, it was found that morphological features such as crystal size are important to achieve high photocurrent and over 20% effi ciencies. [ 15 ] Despite the rapid development, there is still not a systemic work to clearly understand the infl uence of perovskite layer thickness on its morphology, crystal structure, and mobility, particularly on the device performance, which may ravel the puzzle mentioned as above and provide a simple way to modulate the PSC performance.In this paper, the fi lm thickness dependent structural characteristic and optoelectronic property of perovskite CH 3 NH 3 PbI 3 (MAPbI 3 ) were investigated. It was found that the thickness of MAPbI 3 layer around 300 nm can provide a relatively high PCE due to the preferred (110) crystal orientation and increased grain sizes, which provides the most effi cient carrier transport. From the fi eld effect transistor (FET) measurement we also found that the mobility of MAPbI 3 fi lm shows the similar thickness dependencies with PCE, which is mainly dominated by the grain boundary scattering with different crystallization of perovskite and affects the photoelectric effi ciency of perovskite The typical broad absorption features have enabled halide perovskite to be a promising candidate of the next generational solar cell materials. However, the fundamental properties, upon which the photoelectric performance of perovskite device is based, are currently still not clear. Herein, the photovoltaic effi ciencies in perovskite fi lms with various thicknesses have been investigated to reveal a direct correlation between internal structure factors, such as crystal orientation, grain size, and photoelectric perfor...
Cellobiase can hydrolyze cellobiose into glucose; it plays a key role in the process of cellulose hydrolysis by reducing the product inhibition. To reuse the enzyme and improve the economic value of cellulosic ethanol, cellobiase was immobilized using sodium alginate and chitosan as carriers by the bubbling method. The immobilization conditions were optimized as follows: enzyme loading of 100 U cellobiase/g carrier, 30 min immobilization, 3.5 wt% sodium alginate, 0.25 wt% chitosan, and 2 wt% calcium chloride. Compared to free enzyme, the immobilized cellobiase had a decreased apparent K(m) and the maximum activity at a lower pH, indicating its higher acidic and thermal stability. The immobilized cellobiase was further tested in the hydrolysis of cellobiose and various cellulosic substrates (microcrystalline cellulose, filter paper, and ammonia-pretreated corn cobs). Together with cellulases, the immobilized cellobiase converted the cellulosic substrates into glucose with the rate and extent similar to the free enzyme.
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