Amorphous–microcrystalline MoS_(2)thin films are fabricated using the sol-gel method to produce MoS_(2)/Si-based solar cells. The generation mechanisms of the S-shaped current density–voltage(J–V) curves of the sol...Amorphous–microcrystalline MoS_(2)thin films are fabricated using the sol-gel method to produce MoS_(2)/Si-based solar cells. The generation mechanisms of the S-shaped current density–voltage(J–V) curves of the solar cells are analyzed. To improve the performance of the solar cells and address the problem of the S-shaped J–V curve, a MoS_(2)film and a p^(+) layer are introduced into the front and back interfaces of the solar cell, respectively, which leads to the formation of a p–n junction between the p-Si and the MoS_(2)film as well as ohmic contacts between the MoS_(2)film and the ITO, improving the S-shaped J–V curve. As a result of the high doping characteristics and the high work function of the p^(+) layer, a high–low junction is formed between the p;and p layers along with ohmic contacts between the p;layer and the Ag electrode. Consequently,the S-shaped J–V curve is eliminated, and a significantly higher current density is achieved at a high voltage. The device exhibits ideal p–n junction rectification characteristics and achieves a high power-conversion efficiency(CE) of 7.55%. The findings of this study may improve the application of MoS_(2)thin films in silicon-based solar cells, which are expected to be widely used in various silicon-based electronic and optical devices.展开更多
By making use of bifurcation analysis and continuation method, the authors discuss the exact number of positive solutions for a class of perturbed equations. The nonlinearities concerned are the so-called convex-conca...By making use of bifurcation analysis and continuation method, the authors discuss the exact number of positive solutions for a class of perturbed equations. The nonlinearities concerned are the so-called convex-concave functions and their behaviors may be asymptotic sublinear or asymptotic linear. Moreover, precise global bifurcation diagrams are obtained.展开更多
A model of the growth curve of microorganisms was proposed,which reveals a relation-ship with the number of a‘golden section’,1.618…,for main parameters of the growth curves.The treatment mainly concerns the ratio ...A model of the growth curve of microorganisms was proposed,which reveals a relation-ship with the number of a‘golden section’,1.618…,for main parameters of the growth curves.The treatment mainly concerns the ratio of the maximum asymptotic value of biomass in the phase of slow growth to the real value of biomass accumulation at the end of exponential growth,which is equal to thc square of the'golden section',i.e.,2.618.There are a few relevant theorems to explain these facts.New,yet simpler,methods were considered for deterrmining the model parameters based on hyperbolic functions.A comparison was made with one of the alternative models to demonstrate the advantage of the proposed model.The proposed model should be useful to apply at various stages of fermentation in scientific and industrial units.Further,the model could give a new impetus to the development of new mathematical knowledge regarding the algebra of the‘golden section'as a whole,as well as in connection with the introduction of a new equation at decomposing of any roots with any degrees for differences between constants and/or variables.展开更多
基金Project supported by the Science and Technology Research Project of Hebei Province Colleges and Universities (Grant No. QN2020113)Tangshan Applied Basic Research Project (Grant No. 19130227g)。
文摘Amorphous–microcrystalline MoS_(2)thin films are fabricated using the sol-gel method to produce MoS_(2)/Si-based solar cells. The generation mechanisms of the S-shaped current density–voltage(J–V) curves of the solar cells are analyzed. To improve the performance of the solar cells and address the problem of the S-shaped J–V curve, a MoS_(2)film and a p^(+) layer are introduced into the front and back interfaces of the solar cell, respectively, which leads to the formation of a p–n junction between the p-Si and the MoS_(2)film as well as ohmic contacts between the MoS_(2)film and the ITO, improving the S-shaped J–V curve. As a result of the high doping characteristics and the high work function of the p^(+) layer, a high–low junction is formed between the p;and p layers along with ohmic contacts between the p;layer and the Ag electrode. Consequently,the S-shaped J–V curve is eliminated, and a significantly higher current density is achieved at a high voltage. The device exhibits ideal p–n junction rectification characteristics and achieves a high power-conversion efficiency(CE) of 7.55%. The findings of this study may improve the application of MoS_(2)thin films in silicon-based solar cells, which are expected to be widely used in various silicon-based electronic and optical devices.
基金supported by the Foundation of Shanghai Municipal Education Commission (No. 06DZ004).
文摘By making use of bifurcation analysis and continuation method, the authors discuss the exact number of positive solutions for a class of perturbed equations. The nonlinearities concerned are the so-called convex-concave functions and their behaviors may be asymptotic sublinear or asymptotic linear. Moreover, precise global bifurcation diagrams are obtained.
文摘A model of the growth curve of microorganisms was proposed,which reveals a relation-ship with the number of a‘golden section’,1.618…,for main parameters of the growth curves.The treatment mainly concerns the ratio of the maximum asymptotic value of biomass in the phase of slow growth to the real value of biomass accumulation at the end of exponential growth,which is equal to thc square of the'golden section',i.e.,2.618.There are a few relevant theorems to explain these facts.New,yet simpler,methods were considered for deterrmining the model parameters based on hyperbolic functions.A comparison was made with one of the alternative models to demonstrate the advantage of the proposed model.The proposed model should be useful to apply at various stages of fermentation in scientific and industrial units.Further,the model could give a new impetus to the development of new mathematical knowledge regarding the algebra of the‘golden section'as a whole,as well as in connection with the introduction of a new equation at decomposing of any roots with any degrees for differences between constants and/or variables.
