Potential of interdigitated back contact silicon heterojunction solar cells for liquid phase crystallized silicon on glass with efficiency above 14

Liquid phase crystallization of silicon LPC Si on glass is a promising method to produce high quality multi crystalline Si films with macroscopic grains. In this study, we report on recent improvements of our interdigitated back contact silicon heterojunction contact system IBC SHJ , which enabled open circuit voltages as high as 661 mV and efficiencies up to 14.2 using a 13 m thin n type LPC Si absorbers on glass. The influence of the BSF width on the cell performance is investigated both experimentally and numerically. We combine 1D optical simulations using GenPro4 and 2D electrical simulations using Sentaurus TCAD to determine the optical and electrical loss mechanisms in order to estimate the potential of our current LPC Si absorbers. The simulations reveal an effective minority carrier diffusion length of 26 m and further demonstrate that a doping concentration of 4 1016 cm 3 and a back surface field width of 60 m are optimum values to further increase cell efficiencie

State estimation of chemical engineering systems tending to multiple solutions

A well-evaluated state covariance matrix avoids error propagation due to divergence issues and, thereby, it is crucial for a successful state estimator design. In this paper we investigate the performance of the state covariance matrices used in three unconstrained Extended Kalman Filter (EKF) formulations and one constrained EKF formulation (CEKF). As benchmark case studies we have chosen: a) a batch chemical reactor with reversible reactions whose system model and measurement are such that multiple states satisfy the equilibrium condition and b) a CSTR with exothermic irreversible reactions and cooling jacket energy balance whose nonlinear behavior includes multiple steady-states and limit cycles. The results have shown that CEKF is in general the best choice of EKF formulations (even if they are constrained with an ad hoc clipping strategy which avoids undesired states) for such case studies. Contrary to a clipped EKF formulation, CEKF incorporates constraints into an optimization problem, which minimizes the noise in a least square sense preventing a bad noise distribution. It is also shown that, although the Moving Horizon Estimation (MHE) provides greater robustness to a poor guess of the initial state, converging in less steps to the actual states, it is not justified for our examples due to the high additional computational effort

Maximization of propylene in an industrial FCC unit

YesThe FCC riser cracks gas oil into useful fuels such as gasoline, diesel and some lighter products such as ethylene and propylene, which are major building blocks for the polyethylene and polypropylene production. The production objective of the riser is usually the maximization of gasoline and diesel, but it can also be to maximize propylene. The optimization and parameter estimation of a six-lumped catalytic cracking reaction of gas oil in FCC is carried out to maximize the yield of propylene using an optimisation framework developed in gPROMS software 5.0 by optimizing mass flow rates and temperatures of catalyst and gas oil. The optimal values of 290.8 kg/s mass flow rate of catalyst and 53.4 kg/s mass flow rate of gas oil were obtained as propylene yield is maximized to give 8.95 wt%. When compared with the base case simulation value of 4.59 wt% propylene yield, the maximized propylene yield is increased by 95%

Family Businesses and Adaptation: A Dynamic Capabilities Approach

The main objective of this research was to propose a framework centred on the dynamic capabilities approach, and to be applied in the context of family businesses’ adaption to their changing business environment. Data were gathered through interviews with ten FBs operating in Western Australia. Based on the findings, the clusters of activities, sensing, seizing, and transforming emerged as key factors for firms’ adaptation, and were reinforced by firms’ open culture, signature processes, idiosyncratic knowledge, and valuable, rare, inimitable and non-substitutable attributes. Thus, the usefulness of the proposed framework was confirmed. Implications and future research opportunities are presented. © 2018, The Author(s)

Phase transformations of an alumina membrane and its influence on silicon nucleation during the aluminium induced layer exchange

The aluminium induced layer exchange process is used for growing crystalline Si films on amorphous substrates like glass, which are further epitaxially thickened and can be used for photovoltaic applications. In this work we investigated Al2O3 membranes separating the Al and Si layer during the layer exchange by means of high resolution transmission electron microscopy and studied the influence of the membranes structure on crystallization of Si. We observed a phase transformation of the membrane from the amorphous state to amp; 947; Al2O3 at exchange temperatures at above 450 C. At higher temperatures this transformations induces cracks into the thin membrane. We further discuss the influence of this phase transformation on the preferential orientation of the growing Si grains

Aluminium induced crystallisation of amorphous silicon the influence of the aluminium layer on the process

Aluminium Induced Crystallisation of Amorphous Silicon The Influence of the Aluminium Layer on the Proces

Theoretical study of the initial stage of the aluminium induced layer exchange process

In this work, the initial stage of the aluminium induced layer exchange ALILE process is studied theoretically. The diffusion of silicon atoms from an amorphous Si layer into an Al layer through a permeable membrane prior to Si grain nucleation within the Al layer is considered. A kinetic model is derived to describe this process. In the framework of this model, the evolution of the Si concentration within the Al layer prior to Si grain nucleation and the nucleation time are investigated for different annealing temperatures and preparation conditions of the membrane. From the comparison of results of calculations with experimental data, the pre exponent factors and activation energies of diffusion coefficients of Si in membranes are determine

A model of preferential 100 crystal orientation of Si grains grown by aluminium induced layer exchange process

The aluminium induced layer exchange process allows to grow thin large grained polycrystalline Si films on foreign substrates. A characteristic feature of these films is the preferential 100 orientation of Si grains, favourable for subsequent epitaxial thickening at low temperatures. In this work, a model based on the preferential nucleation is proposed, which elucidates a possible origin of the preferential 100 orientation and its sensitivity to the preparation and process conditions. The probability of Si nuclei to have respective orientation is attributed to the nucleation barrier, i.e. the critical value of the change of the Gibbs energy during nucleation. The preferential orientation is formed statistically by the nuclei having the lowest nucleation barrier