Nanoscale Photovoltaic Responses in 3D Radial Junction Solar Cells Revealed by High Spatial Resolution Laser Excitation Photoelectric Microscopy

Abstract

The actual light absorption photovoltaic responses realized in three-dimensional (3D) radial junction (RJ) units can be rather different from their planar counterparts and remain largely unexplored. We here adopt a laser excitation photoelectric microscope (LEPM) technology to probe the local light harvesting and photoelectric signals of 3D hydrogenated amorphous silicon (a-Si:H) RJ thin film solar cells constructed over a Si nanowire (SiNW) matrix, with a high spatial resolution of 600 nm thanks to the use of a high numerical aperture objective. The LEPM scan can help to resolve clearly the impacts of local structural damages, which are invisible to optical and SEM observations. More importantly, the high-resolution photoelectric mapping establishes a straightforward link between the local 3D geometry of RJ units and their light conversion performance. Surprisingly, it is found that the maximal photoelectric signals are usually recorded in the void locations among the standing SiNW RJs, instead of the overhead positions above the RJs. This phenomenon can be well explained and reproduced by finite element simulation analysis, which highlights unambiguously the dominant contribution of inter-RJ-unit scattering against direct mode incoupling in the 3D solar cell architecture. This LEPM mapping technology and the results help to achieve a straightforward and high-resolution evaluation of the local photovoltaic responses among the 3D RJ units, providing a solid basis for further structural optimization and performance improvement.

Helical SiNW design with a dual-peak response for broadband scattering in translucent solar cells

“…Helical SiNWs can also be designed as axial or radial junction solar cells, which can give full play to the electrical advantages of SiNWs and be used as micro power supply in electrical components. 35,36 In addition, in the calculation process of this work, it is also found that helical SiNWs have the selectivity of polarized light, which is similar to other helical nanowire structures and can be used in optical devices.…”

3D Radial Junctions for Robust and Flexible Optoelectronics

“…Recently, a laser excitation photoelectric microscope (LEPM) technology has been adopted by H. Zhang et al to directly detect the local light-harvesting behavior and photoelectric signals of RJ units with a smaller size of 4 μm wide, [149] as presented in Figure 9a, as and d) corresponding signal intensity. [149] Copyright 2019 American Chemical Society.…”

New Hybrid Light Harvesting Antenna Based on Silicon Nanowires and Metal Dendrimers

“…These systems are characterized by an efficient photo induced downhill energy transfer from the nanostructured material to the dyes, and in this field the term antenna commonly refers to this behavior [ 36–39 ] and not to antenna or resonant modes as it is used in the photovoltaic field. [ 40,41 ] In particular, Si nc has been studied obtaining energy transfer efficiencies of 65% generally by using chromophores concentrations of a few m m , with the perspective of increment by functionalization procedure. [ 32 ]…”