Perovskite-based color camera inspired by human visual cells

There are two primary types of photoreceptor cells in the human eye:cone cells and rod cells that enable color vision and night vision,respectively.Herein,inspired by the function of human visual cells,we develop a high-resolution perovskite-based color camera using a set of narrowband red,green,blue,and broadband white perovskite photodetectors as imaging sensors.The narrowband red,green,and blue perovskite photodetectors with color perceptions mimic long-,medium-,and short-wavelength cones cells to achieve color imaging ability.Also,the broadband white perovskite photodetector with better detectivity mimics rod cells to improve weak-light imaging ability.Our perovskite-based camera,combined with predesigned pattern illumination and image reconstruction technology,is demonstrated with high-resolution color images(up to 256 x 256 pixels)in diffuse mode.This is far beyond previously reported advanced perovskite array image sensors that only work in monochrome transmission mode.This work shows a new approach to bio-inspired cameras and their great potential to strongly mimic the ability of the natural eve.

Influence of using amorphous silicon stack as front heterojunction structure on performance of interdigitated back contact-heterojunction solar cell （IBC-HJ）

Interdigitated back contact-heterojunction （IBC-HJ） solar cells can have a conversion efficiency of over 25%. However, the front surface passivation and structure have a great influence on the properties of the IBC-HJ solar cell. In this paper, detailed numerical simulations have been performed to investigate the potential of front surface field （FSF） offered by stack of n-type doped and intrinsic amorphous silicon （a-Si） layers on the front surface of IBC-HJ solar cells. Simulations results clearly indicate that the electric field of FSF should be strong enough to repel minority carries and cumulate major carriers near the front surface. However, the overstrong electric field tends to drive electrons into a-Si layer, leading to severe recombination loss. The n-type doped amorphous silicon （n-a-Si） layer has been optimized in terms of doping level and thickness. The optimized intrinsic amorphous silicon （i-a-Si） layer should be as thin as possible with an energy band gap （Es） larger than 1.4 eV. In addition, the simulations concerning interface defects strongly suggest that FSF is essential when the front surface is not passivated perfectly. Without FSF, the IBC-HJ solar cells may become more sensitive to interface defect density.

Boron-rich layer removal and surface passivation of boron-doped p–n silicon solar cells

In boron-doped p+-n crystalline silicon（Si） solar cells, p-type boron doping control and surface passivation play a vital role in the realization of high-efficiency and low cost pursuit. In this study, boron-doped p+-emitters are formed by boron diffusion in an open-tube furnace using borontribromide（BBr3） as precursor. The formed emitters are characterized in detail in terms of shape of the doping profile, surface doping concentration, junction depth, sheet resistance and removal of the boron-rich layer（BRL）. In the aspect of BRL removal, three different methods were adopted to investigate their influence on device performance. The results demonstrate that our proposed chemical etch treatment（CET） with the proper etching time could be an effective way to remove the BRL.After removal of the BRL, Al;O;/SiN;stacks are deposited by atomic layer deposition（ALD） and plasma-enhanced chemical vapor deposition（PECVD） to passivate the cell surface. It was found that a reasonably-high implied Voc of 680 mV has been achieved for the fabricated n-type Si solar cells.