To realize a high-performance solid-state photon-enhanced thermionic emission (SPETE) solar energy converter, in this study, a graded bandgap window layer is therefore adopted, throughout which the bandgap gradation is generated via the variation of Al composition in the A l x G a 1 − x As layer in the SPETE converter with a GaAs absorber. Based on one-dimension steady-state equation, an analytical model is formed in analyzing performance of the proposed device in our study. Theoretical simulation results indicate that not only are the losses of contact surface recombination being decreased via the bandgap-gradation-induced build-in electric field of the window layer, but also the photon-generated electrons are effectively collected, thereby improving the conversion efficiency. Moreover, the effect of bandgap energy of the contact surface and the width of the window layer on device performance is discussed. A trade-off of high-efficient SPETE converters is therefore realized between large contact surface bandgap and thin window layer width, to which the rationale lies in the improved process of electron collection facilitated by the enhanced build-in electric field rather than reducing the photon absorption in the window layer. Threshold values for barrier height at the emitting interface are presented to guarantee the ideal voltage-current characteristic. It is found that the threshold values of barrier increase with the increase in temperatures.

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This study proposes a comprehensive model of the circular arc terminated (CAT) resistive anode based on the finite element method to explore the dynamic process of charge diffusion on this anode and its position linearity performance. The waveforms of charges of the electrodes on the anode are calculated for different electrical parameters and their influence on positional linearity is investigated. The influence of the signal development time and the non-uniformity of the resistance per square of the anode on positional linearity is also analyzed. The results of simulations show that the non-linearity of the image varies monotonically with the termination resistance and the non-uniformity of the resistance per square of the anode, but has a non-linear relationship with the signal development time and the ratio of the resistance per square. A CAT resistive anode with capacitance c and a resistance per square of the sensitive area of R▱ can be used to recover an image with a root mean-squared non-linearity of 2%, when the charge signals of the electrode are collected for at least 0.6 R▱ c s. The reliability of the results of the simulations was verified with experimental measurements.