Construction and Implementation of Institutional E-learning Development Framework in Continuing Higher Education

E-learning has become a popular teaching and learning mode in the education and training sectors in the digital age. Many studies have been done in the field of e-learning at course level. However, limited literature has been found about e-learning strategic development in continuing higher education sector at the institutional level. The purpose of this study was to explore the institutional development and implementation of e-learning, using the School of Professional and Continuing Education at the University of Hong Kong (HKU SPACE) as a case. In this paper, the comprehensive e-learning development framework at institutional level is proposed and seven dimensions under the framework are explored, including e-learning policy, e-learning organizational structure, e-learning systems, m-learning APP, e-learning courses, e-learning training and support, and e-learning evaluation. Based on the results of the case study, it is suggested that policy and organizational structure are essential to ensure the implementation of e-learning in self-financed continuing higher education institutions. The e-learning systems, m-learning applications, e-courses, training and support, and e-learning evaluation should be considered and integrated as a whole in order to maintain continuous development and enhancement in e-learning.It is hoped that the institutional e-learning development framework presented in this paper can provide a benchmark for continuing higher education institutions to make e-learning strategic planning

Laminated Monolithic Perovskite/Silicon Tandem Photovoltaics

Perovskite/silicon tandem photovoltaics have attracted enormous attention in science and technology over recent years. In order to improve the performance and stability of the technology, new materials and processes need to be investigated. However, the established sequential layer deposition methods severely limit the choice of materials and accessible device architectures. In response, a novel lamination process that increases the degree of freedom in processing the top perovskite solar cell (PSC) is proposed. The very first prototypes of laminated monolithic perovskite/silicon tandem solar cells with stable power output efficiencies of up to 20.0% are presented. Moreover, laminated single-junction PSCs are on par with standard sequential layer deposition processed devices in the same architecture. The numerous advantages of the lamination process are highlighted, in particular the opportunities to engineer the perovskite morphology, which leads to a reduction of non-radiative recombination losses and and an enhancement in open-circuit voltage (Voc). Laminated PSCs exhibit improved stability by retaining their initial efficiency after 1-year aging and show good thermal stability under prolonged illumination at 80 °C. This lamination approach enables the research of new architectures for perovskite-based photovoltaics and paves a new route for processing monolithic tandem solar cells even with a scalable lamination process

Utilization of ultra-thin n-type Hydrogenated Nanocrystalline Silicon for Silicon Heterojunction Solar Cells

To optimize the electrical performance of silicon heterojunction solar cell devices, the electronic properties and microstructure of n-type nc-Si:H were characterized and analyzed. It was found that higher conductivity and crystalline volume fraction (Fc) of nc-Si:H can be obtained at lower silane gas fraction (fSiH4), lower power and higher phosphorous gas fraction (fPH3). In our case, there is a decline of the passivation for the devices with nc-Si:H after sputtering process. By increasing the phosphine flow fraction, the sputter damage can be reduced and 3%abs gain of FF as well as 0.7%abs gain of efficiency is reached compared with reference. The best solar cell exhibits the Voc of 733.3 mV, FF of 79.7%, Jsc of 39.00 mA/cm2 and η of 22.79% at the M2 size wafer

Influence of Room Temperature Sputtered Al-Doped Zinc Oxide on Passivation Quality in Silicon Heterojunction Solar Cells

Al-doped zinc oxide (AZO) is a potential candidate to substitute tin-doped indium oxide in silicon heterojunction (SHJ) solar cells due to its low cost and low ecological impact. The AZO, sputtered at room temperature (RT), is of particular interest because of low thermal budget and potential for high throughput production with the well-established industrial methods. In SHJ solar cells, high effective carrier lifetime prerequisite for the high open-circuit voltage is achieved with surface passivation by intrinsic amorphous silicon layers followed by doped silicon layers. The passivation quality may be affected by the subsequent sputtering of an AZO layer especially at RT. In this article, we investigated the influence of the AZO sputtering and postdeposition annealing on the effective carrier lifetime in symmetrical silicon layer stacks with n- or p-type doped silicon layers and solar cell precursors. It has been found that the effective carrier lifetime significantly decreased after AZO sputtering at RT. The detrimental effect of AZO sputtering is substrate temperature dependent and is smaller or even absent at elevated temperatures. However, postdeposition annealing, equivalent to the Ag paste curing, mostly recovered the effective carrier lifetime in the symmetrical stacks as well as in the cell precursors. Finally, an aperture area efficiency of 21.2% has been achieved for the 19 mm × 19 mm SHJ solar cell prepared with room temperature sputtered AZO