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1.
Campbell Syst Rev ; 19(4): e1370, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38089569

RESUMEN

Background: Financial incentives for chief executive officers (CEOs) are thought to motivate them to lead their company toward achieving important business objectives. Based on the Rousseau et al. (2019) protocol, this systematic review assesses the predictive effects of CEO incentives on certain business outcomes. Objectives: This review addresses whether CEO financial incentives predict: (1) firm financial performance and (2) financial restatement due to misreporting. Search methods: We searched nine research databases for published peer-reviewed literature (to July 23-26, 2021 and an attenuated search from those dates to July 27-31, 2023) and thirteen professional association websites for non-published gray literature (to August 2021). We also hand-searched selected relevant journals. Selection criteria: We reviewed peer-reviewed and unpublished studies available in English since 1980. Eligible studies regarding our first question assessed CEO financial incentives (1) 1 year or more before the measurement of outcomes, (2) controlled for pre-incentive firm performance or market conditions, and (3) analyzed CEO financial incentives as predictors of firm outcomes. Eligible studies regarding our second question assessed whether financial restatement had occurred and analyzed effects of CEO incentives on this outcome. Data collection and analysis: We extracted standardized regression coefficients for each effect or converted unstandardized regressions to standardized. Analyses were conducted using STATA. All studies were assessed to have moderate risk of bias. Main results: For our first question, 20 studies (15,398 firms) met our criteria for meta-analysis of effects. Bonuses, the most commonly studied incentive, had a small positive effect on next year's accounting performance metric Return on Assets (ROA, 0.046 [k = 7, 95% confidence interval (CI) = 0.014, 0.078]). The bonus effect in the market-related metric of Stock Returns (-0.026 [k = 5, 95% CI = -0.119, 0.067]) fell within a CI including 0, as did its effect on another market-related metric, Market-to-Book value (Tobin's Q, 0.028 [k = 3, 95% CI = -0.024, 0.08]). We conclude that Bonuses show no predictive effect on the following year's market-related metrics but do affect ROA. Stock Options had no effect on next year's ROA (0.027 [k = 5, 0.95% CI = 0.000, 0.052]), nor on Market-to-Book Value (Tobin's Q, 0.097 [k = 5, 95% CI = -0.027, 0.220]) or Stock Return (0.042 [k = 6, -0.033, 0.117]), indicating no predictive effect for Stock Options on either accounting or market-related performance. We sought but found too few studies to report on effects of incentives on other financial outcomes or for lags greater than 1 year. For our second question, three studies (n = 2044 firms) met our criteria. The overall effect size for CEO Incentives on Restatement (-0.09 [k = 3, 95% CI = -0.363, 0.184) fell within a CI including zero. We conclude that current evidence does not support a direct relationship between CEO financial incentives and Restatement. Authors' conclusions: This review affirms a small effect of CEO Bonuses, but no effect of Stock Options, on the accounting performance metric ROA. In contrast, neither Bonuses nor Stock Options predict a firm's market-related metrics. CEO incentives also are unrelated to Financial Restatement. Despite widespread use of CEO financial incentives, lack of evidence supporting their use, beyond the bonus-ROA effect we identify, suggests caution regarding current CEO financial incentive practice and greater consideration of alternative arrangements to enhance firm performance.

2.
ACS Appl Energy Mater ; 6(11): 5720-5728, 2023 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-37323208

RESUMEN

Di(9-methyl-3-carbazolyl)-(4-anisyl)amine is presented as an effective hole-transporting material suitable for application in perovskite solar cells. It is obtained by a three-step synthesis from inexpensive starting compounds. It has a relatively high glass transition temperature of 93 °C and thermal stability with 5% weight loss at 374 °C. The compound exhibits reversible double-wave electrochemical oxidation below +1.5 V and polymerization at higher potential. A mechanism for its oxidation is proposed based on electrochemical impedance and electron spin resonance spectroscopy investigations, ultraviolet-visible-near-infrared absorption spectroelectrochemistry results, and density functional theory-based calculations. Vacuum-deposited films of the compound are characterized by a low ionization potential of 5.02 ± 0.06 eV and hole mobility of 10-3 cm2/(Vs) at an electric field of 4 × 105 V/cm. The newly synthesized compound has been used to fabricate dopant-free hole-transporting layers in perovskite solar cells. A power conversion efficiency of 15.5% was achieved in a preliminary study.

3.
J Immigr Minor Health ; 24(4): 956-962, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34787804

RESUMEN

Drawing on the social-ecological systems perspective of health, this study explores whether the deteriorating trend of immigrant health over time differs depending on immigrants' pre-migration macro-level factors in their birth country. Using the Household, Income, and Labor Dynamics in Australia survey (N = 1,847), we conducted an HLM analysis to examine the association among GDP per capita in the birth country, length of stay, and immigrants' health status post-migration. Support was found for both the negative association between the length of stay and health and the positive association between the GDP of the birth country and health. The negative association between length of stay and health was stronger among immigrants from low GDP countries compared to those from high GDP countries. Our findings suggest the importance of the population-level characteristics of the birth country in understanding healthy immigrant effect post-migration.


Asunto(s)
Emigrantes e Inmigrantes , Empleo , Estado de Salud , Humanos , Renta , Factores Socioeconómicos
4.
Nanoscale ; 13(26): 11478-11487, 2021 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-34165116

RESUMEN

The cesium cation (Cs+) is widely used as a dopant for highly efficient and stable formamidinium lead tri-halide perovskite (FAPbX3, X = I, Br, Cl) solar cells. Herein, we introduce a small amount of cesium acetate (CsAc) that can effectively stabilize FAMAPbI3 under thermal- and light illumination-stress. We show that incorporated Cs+ leads to relaxation of strain in the perovskite layer, and that Ac- forms a strong intermediate phase with PbI2, which can help the intercalation of the PbI2 film with Cs+ and cation halide (FAI, MAI, MACl) in the sequential deposition process. The addition of CsAc reduces the trap density in the resulting perovskite layers and extends their carrier lifetime. The CsAc-modified perovskite solar cells show less hysteresis phenomena and enhanced operational and thermal stability in ambient conditions. Our findings provide insight into how dopants and synthesis precursors play an important role in efficient and stable perovskite solar cells.

5.
J Back Musculoskelet Rehabil ; 34(1): 95-101, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33104016

RESUMEN

BACKGROUND: Problems related to ankle instability, decreased proprioceptive sensation, altered static and dynamic balance abilities are suggested as major representative factors that contribute to the recurrence of ankle sprains. OBJECTIVE: To assess the effect of a three-week intervention (intervention emphasizing diagonal eccentric contraction (IEDEC) and intervention of general exercise (IGE)) on static and dynamic balance abilities, ankle strength and joint position sense at pre- and post-intervention, and at two- and three-week post-intervention. METHODS: Twenty-five participants with ankle instability, including a history of ankle sprain and recurrent episodes of giving way, were enrolled in the study. They were randomly classified into the IEDEC group (n= 12) and the IGE group (n= 13). Dynamic balance was examined using the Y Balance Test, four-way ankle strength was measured, and the static balance was evaluated using the total displacement of the center of pressure (COP). To identify the joint position error, eversion and inversion of the ankle angle were measured. RESULTS: The results revealed significant increases in ankle dynamic stability and strength at two and three weeks post-intervention (p< 0.05). Similarly, the total displacement of the COP differed significantly over time, with a higher COP during the initial measurement than at two and three weeks intervention (p< 0.05) General balance training with IEDEC can improve position sense during ankle inversion (p< 0.05). CONCLUSION: General balance training with IEDEC improved the position sense of the inversion. Combined therapeutic intervention, such as with the manual technique, could be a beneficial approach to maximize the treatment effects.


Asunto(s)
Traumatismos del Tobillo/prevención & control , Articulación del Tobillo/fisiopatología , Tobillo/fisiopatología , Inestabilidad de la Articulación/terapia , Contracción Muscular/fisiología , Modalidades de Fisioterapia , Propiocepción/fisiología , Adulto , Femenino , Humanos , Inestabilidad de la Articulación/fisiopatología , Masculino , Equilibrio Postural/fisiología , Resultado del Tratamiento , Adulto Joven
6.
ACS Appl Mater Interfaces ; 12(6): 7125-7134, 2020 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-31958005

RESUMEN

Perovskite solar cells (PSCs), which have surprisingly emerged in recent years, are now aiming at commercialization. Rapid, low-temperature, and continuous fabrication processes that can produce high-efficiency PSCs with a reduced fabrication cost and shortened energy payback time are important challenges on the way to commercialization. Herein, we report a reactive ion etching (RIE) method, which is an ultrafast room-temperature technique, to fabricate mesoporous TiO2 (mp-TiO2) as an electron transport layer for high-efficiency PSCs. Replacing the conventional high-temperature annealing process by RIE reduces the total processing time for fabricating 20 PSCs by 40%. Additionally, the RIE-processed mp-TiO2 exhibits enhanced electron extraction, whereupon the optimized RIE-mp-TiO2-based PSC exhibits a power conversion efficiency (PCE) of 19.60% without J-V hysteresis, when the devices were optimized with a TiCl4 surface treatment process. Finally, a flexible PSC employing RIE-mp-TiO2 is demonstrated with 17.29% PCE. Considering that the RIE process has been actively used in the semiconductor industry, including for the fabrication of silicon photovoltaic modules, the process developed in this work could be easily applied toward faster, simpler, and cheaper manufacturing of PSC modules.

7.
ACS Appl Mater Interfaces ; 11(51): 48497-48504, 2019 Dec 26.
Artículo en Inglés | MEDLINE | ID: mdl-31799829

RESUMEN

For commercialization of perovskite solar cells (PSCs), it is important to substitute the alternative electrode for Au to decrease the unit cost. From the early stage, Ag exhibits a potential to be a good counter electrode in PSCs; however, there is an abnormal s-shaped J-V curve with the Ag electrode, and it is recovered as time passes. The perception of the aging-induced recovery process and refutation of the raised stability issues are required for commercial application of Ag electrodes. Herein, we compared the aging effect of PSCs with Ag and Au electrodes and found that only devices with Ag electrodes have a dramatical aging-induced recovery process. We observed the change of photoelectronic properties only in the devices with Ag electrodes as time passes, which mainly contributes to recovery of the s-shaped J-V curve. We verified the work function change of an aged Ag electrode and its mechanism by photoelectron spectroscopy analysis. By comparing the light stability under 1 sun intensity illumination, we can assure the practical stability of Ag electrodes in case of being encapsulated. This work suggests the profound understanding of the aging-induced recovery process of PSCs and the possibility of commercial application of Ag electrodes.

8.
Nanoscale ; 11(41): 19488-19496, 2019 Nov 07.
Artículo en Inglés | MEDLINE | ID: mdl-31552996

RESUMEN

Electron selective layers are important to the efficiency, stability and hysteresis of perovskite solar cells. Photo-annealing is a low-cost, roll-to-roll-compatible process that can be applied to the post-treatment fabrication of sol-gel based metal oxide layers. Here, we fabricate an amorphous titanium oxide electron selective layer at a low temperature in a dry atmosphere using a UV light annealing system and compare it with a thermal annealing process. Active oxygen species are created by using UV light to promote hydrolysis and condense the TiO2 precursor, which removes organic ligands effectively. The photo-annealed TiO2-based perovskite solar cell has a power conversion efficiency of 19.37% without hysteresis.

9.
Adv Mater ; 30(49): e1802763, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30306647

RESUMEN

Photovoltaic technologies based on perovskite absorber materials have led this optoelectronic field into a brand-new horizon. However, the present antisolvents used in the one-step spin-coating method always encounter problems with the very narrow process window. Herein, anisole is introduced into the one-step spin-coating method, and the technology is developed to fabricate perovskite thin films with ultrawide processing window with a dimethylformamide (DMF):dimethyl sulfoxide (DMSO) ratio varying from 6:4 to 9:1 in the precursor solution, anisole dripping time ranging from 5 to 25 s, and an antisolvent volume varying from 0.1 to 0.9 mL. Perovskite thin films as large as 100 cm2 are successfully fabricated using this method. Maximum photoelectric conversion efficiencies of 19.76% for small-area (0.14 cm2 ) and 17.39% for large-area (1.08 cm2 ) perovskite solar cell devices are obtained. It is also found that there are intermolecular hydrogen-bonding forces between anisole and DMF/DMSO that play critical roles in the wide process window. These results provide a deeper understanding of the crystallizing procedure of perovskite during the one-step spin-coating process.

10.
J Phys Ther Sci ; 30(8): 1073-1080, 2018 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-30154603

RESUMEN

[Purpose] This study was conducted to examine the effects of task-specific movement patterns during resistance exercise program, which are applied to children with cerebral palsy, on respiratory functions and thickness of abdominal muscles. [Participants and Methods] This study was conducted with randomized double-blinded controlled research was pursued since it is a clinical trial with minors with disabilities as the participants. Seventeen children with cerebral palsy were randomly allocated to both experimental group and placebo group by means of simple randomized sampling. The experimental group wore weighted vest to which loaded-resistance was applied by means of sand bag while the placebo group wore weighted vest without loaded-resistance. Task-specific movement patterns during resistance exercise were performed for 40 minutes 2 times a week over a period of 12 weeks for the participants in both groups. Differences in respiratory functions and thickness of abdominal muscles measured prior to and after 12 weeks of the experiment were compared. [Results] All the measurement values for the respiratory functions and abdominal muscle thickness displayed statistically significant changes between those prior to and after the exercise in both of the experimental group and the placebo group. There were statistically significant differences in the changes prior to and following the exercise between the two groups. [Conclusion] Therefore, task-specific movement patterns in anatomical plane, diagonal patterns and combined forms during resistance exercise program on for children with cerebral palsy can be considered as an efficient intervention method in improving respiratory capacity.

11.
J Exerc Rehabil ; 14(6): 998-1004, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30656161

RESUMEN

This study was executed as correlation study to investigate the correlation between the dimensions of diaphragm movement, and respiratory functions and pressures in accordance with the Gross Motor Function Classification System (GMFCS) levels on children with cerebral palsy as the participants. Forty-three children in the age range of 5-13 years diagnosed with cerebral palsy as the research participants were divided into three groups (levels I, II, and III) through systematic stratified random sampling in accordance with their GMFCS levels. Pearson correlation analysis was executed to examine the correlation between dimensions of diaphragm movement, and respiratory functions and pressures in accordance with the GMFCS levels of the participants. There was no significant correlation between the dimensions of diaphragm movement, and respiratory functions and pressures in all of the three groups in accordance with the GMFCS levels of the participants. Therefore, it is deemed that although measurement of the dimensions of diaphragm movement of children with cerebral palsy by using diagnostic ultrasonic M-mode imaging device can be considered as auxiliary tool in predicting the breathing capabilities, it cannot be used as independent measurement equipment.

12.
Nanotechnology ; 28(31): 315402, 2017 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-28707623

RESUMEN

The electrical properties of CH3NH3Pb(I1-x Br x )3 (x = 0.13) perovskite materials were investigated under ambient conditions. The local work function and the local current were measured using Kelvin probe force microscopy and conductive atomic force microscopy, respectively. The degradation of the perovskite layers depends on their grain size. As the material degrades, an additional peak in the surface potential appears simultaneously with a sudden increase and subsequent relaxation of the local current. The potential bending at the grain boundaries and the intragrains is the most likely reason for the change of the local current surface of the perovskite layers. The improved understanding of the degradation mechanism garnered from this study helps pave the way toward an improved photo-conversion efficiency in perovskite solar cells.

13.
J Exerc Rehabil ; 13(2): 206-209, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-28503534

RESUMEN

In this study, we examine the thickness of the abdominal muscle and its activity during the performance of the three drawing-in methods. The subjects were 20 healthy male and female students in their 20s. Using ultrasonography and electromyography, the experimenter measured the thickness of the transversus abdominis (TrA) muscle, internal oblique (IO) muscle and external oblique (EO) muscle. The ultrasonography measurements for the drawing-in manoeuver (DI), abdominal bracing, and posterior pelvic tilt (PT) techniques were 0.64±0.20, 0.54±0.15, and 0.46±0.12, respectively, with significant differences for the TrA. The electromyography results of the DI, SA, and PT techniques were 4.35±1.72, 3.00±1.48, and 2.70±1.52, respectively, for the IO. There was a significant difference in the DI, SA, and PT techniques for the EO (5.10±3.30, 3.85±3.89, 2.25±1.29, respectively). The DI method activated the oblique abdominal muscles, but there was no great change in their thickness; the TrA, however, was selectively strengthened through changes in its thickness.

14.
J Phys Ther Sci ; 29(12): 2184-2189, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-29643601

RESUMEN

[Purpose] This study was carried out to examine the effect of the application of group exercise program composed to induce interests and assertive participation of adults with cerebral palsy on the self-efficacy and activities of daily living, as well as to provide basic clinical data that are effective and trustworthy in enhancing the physical and emotional interaction in the future. [Subjects and Methods] Those among the 23 adult with cerebral palsy who are the subjects of research and able to participate only in the evaluation of measurement tools prior to and after the experiment were allocated to the control group while only those who can participate in the group exercise program implemented over 12 sessions were allocated to the experimental group. For the control group, a range of motion of joint exercise and stretching exercise were executed on the arms, legs and trunk, while for the experimental group, group exercise that is implemented with participation of several subjects simultaneously was executed 2 times a week with 40 minutes for each session over a period of 6 weeks for the total of 12 sessions. [Results] In both the experimental group and the control group, there were statistically significant changes in the average scores of self-efficacy and activities of daily living after the exercise in comparison to that prior to the exercise. Moreover, there were statistically significant differences in self-efficacy and activities of daily living in terms of quantity of change prior to and after the exercise between the two groups. [Conclusion] Therefore, group exercise program composed to induce physical and emotional interaction, and active participation of adults with cerebral palsy can be considered as an effective intervention method in improving their self-efficacy and activities of daily living.

15.
ACS Appl Mater Interfaces ; 9(2): 1479-1487, 2017 Jan 18.
Artículo en Inglés | MEDLINE | ID: mdl-27989115

RESUMEN

Coupling dissimilar oxides in heterostructures allows the engineering of interfacial, optical, charge separation/transport and transfer properties of photoanodes for photoelectrochemical (PEC) water splitting. Here, we demonstrate a double-heterojunction concept based on a BiVO4/WO3/SnO2 triple-layer planar heterojunction (TPH) photoanode, which shows simultaneous improvements in the charge transport (∼93% at 1.23 V vs RHE) and transmittance at longer wavelengths (>500 nm). The TPH photoanode was prepared by a facile solution method: a porous SnO2 film was first deposited on a fluorine-doped tin oxide (FTO)/glass substrate followed by WO3 deposition, leading to the formation of a double layer of dense WO3 and a WO3/SnO2 mixture at the bottom. Subsequently, a BiVO4 nanoparticle film was deposited by spin coating. Importantly, the WO3/(WO3+SnO2) composite bottom layer forms a disordered heterojunction, enabling intimate contact, lower interfacial resistance, and efficient charge transport/transfer. In addition, the top BiVO4/WO3 heterojunction layer improves light absorption and charge separation. The resultant TPH photoanode shows greatly improved internal quantum efficiency (∼80%) and PEC water oxidation performance (∼3.1 mA/cm2 at 1.23 V vs RHE) compared to the previously reported BiVO4/WO3 photoanodes. The PEC performance was further improved by a reactive-ion etching treatment and CoOx electrocatalyst deposition. Finally, we demonstrated a bias-free and stable solar water-splitting by constructing a tandem PEC device with a perovskite solar cell (STH ∼3.5%).

16.
Nano Lett ; 16(9): 5756-63, 2016 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-27500375

RESUMEN

Enhancing hole extraction inside the perovskite layer is the key factor for boosting photovoltaic performance. Realization of halide concentration gradient perovskite materials has been expected to exhibit rapid hole extraction due to the precise bandgap tuning. Moreover, a formation of Br-rich region on the tri-iodide perovskite layer is expected to enhance moisture stability without a loss of current density. However, conventional synthetic techniques of perovskite materials such as the solution process have not achieved the realization of halide concentration gradient perovskite materials. In this report, we demonstrate the fabrication of Br concentration gradient mixed halide perovskite materials using a novel and facile halide conversion method based on vaporized hydrobromic acid. Accelerated hole extraction and enhanced lifetime due to Br gradient was verified by observing photoluminescence properties. Through the combination of secondary ion mass spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopy analysis, the diffusion behavior of Br ions in perovskite materials was investigated. The Br-gradient was found to be eventually converted into a homogeneous mixed halide layer after undergoing an intermixing process. Br-substituted perovskite solar cells exhibited a power conversion efficiency of 18.94% due to an increase in open circuit voltage from 1.08 to 1.11 V and an advance in fill-factor from 0.71 to 0.74. Long-term stability was also dramatically enhanced after the conversion process, i.e., the power conversion efficiency of the post-treated device has remained over 97% of the initial value under high humid conditions (40-90%) without any encapsulation for 4 weeks.

17.
Nat Commun ; 7: 11735, 2016 05 23.
Artículo en Inglés | MEDLINE | ID: mdl-27211006

RESUMEN

Most research on perovskite solar cells has focused on improving power-conversion efficiency and stability. However, if one could refurbish perovskite solar cells, their stability might not be a critical issue. From the perspective of cost effectiveness, if failed, perovskite solar cells could be collected and recycled; reuse of their gold electrodes and transparent conducting glasses could reduce the price per watt of perovskite photovoltaic modules. Herein, we present a simple and effective method for removing the perovskite layer and reusing the mesoporous TiO2-coated transparent conducting glass substrate via selective dissolution. We find that the perovskite layer can be easily decomposed in polar aprotic solvents because of the reaction between polar aprotic solvents and Pb(2+) cations. After 10 cycles of recycling, a mesoporous TiO2-coated transparent conducting glass substrate-based perovskite solar cell still shows a constant power-conversion efficiency, thereby demonstrating the possibility of recycling perovskite solar cells.

18.
Nanoscale ; 7(48): 20725-33, 2015 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-26602588

RESUMEN

The spin-coating method, which is widely used for thin film device fabrication, is incapable of large-area deposition or being performed continuously. In perovskite hybrid solar cells using CH(3)NH(3)PbI(3) (MAPbI(3)), large-area deposition is essential for their potential use in mass production. Prior to replacing all the spin-coating process for fabrication of perovskite solar cells, herein, a mesoporous TiO(2) electron-collection layer is fabricated by using the electro-spray deposition (ESD) system. Moreover, impedance spectroscopy and transient photocurrent and photovoltage measurements reveal that the electro-sprayed mesoscopic TiO(2) film facilitates charge collection from the perovskite. The series resistance of the perovskite solar cell is also reduced owing to the highly porous nature of, and the low density of point defects in, the film. An optimized power conversion efficiency of 15.11% is achieved under an illumination of 1 sun; this efficiency is higher than that (13.67%) of the perovskite solar cell with the conventional spin-coated TiO(2) films. Furthermore, the large-area coating capability of the ESD process is verified through the coating of uniform 10 × 10 cm(2) TiO(2) films. This study clearly shows that ESD constitutes therefore a viable alternative for the fabrication of high-throughput, large-area perovskite solar cells.

19.
Nanoscale ; 7(37): 15284-90, 2015 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-26324759

RESUMEN

We demonstrate high-performance perovskite solar cells with excellent electron transport properties using a one-dimensional (1D) electron transport layer (ETL). The 1D array-based ETL is comprised of 1D SnO2 nanowires (NWs) array grown on a F:SnO2 transparent conducting oxide substrate and rutile TiO2 nanoshells epitaxially grown on the surface of the 1D SnO2 NWs. The optimized devices show more than 95% internal quantum yield at 750 nm, and a power conversion efficiency (PCE) of 14.2%. The high quantum yield is attributed to dramatically enhanced electron transport in the epitaxial TiO2 layer, compared to that in conventional nanoparticle-based mesoporous TiO2 (mp-TiO2) layers. In addition, the open space in the 1D array-based ETL increases the prevalence of uniform TiO2/perovskite junctions, leading to reproducible device performance with a high fill factor. This work offers a method to achieve reproducible, high-efficiency perovskite solar cells with high-speed electron transport.

20.
J Phys Chem Lett ; 6(12): 2355-62, 2015 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-26266617

RESUMEN

We fabricated a mesoporous perovskite solar cell with a ∼14% conversion efficiency, and we investigated its beneficial grain boundary properties of the perovskite solar cells through the use of scanning probe microscopy. The CH3NH3Pb(I0.88,Br0.12)3 showed a significant potential barrier bending at the grain boundary and induced passivation. The potential difference value in the x = 0.00 sample is ∼50 mV, and the distribution of the positive potential is lower than that of the x = 0.12 sample. We also investigated the polarization and hysteretic properties of the perovskite thin films by measuring the local piezoresponse. Specifically, the charged grain boundaries play a beneficial role in electron-hole depairing and in suppressing recombination in order to realize high-efficiency perovskite solar cells.

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