3D Radial Junctions for Robust and Flexible Optoelectronics

Abstract

Marrying nanostructures with thin films is a recent trend in flexible optoelectronics to improve light trapping and mechanical stability. Radial junction (RJ) a‐Si:H thin film optoelectronics, directly deposited upon the vapor‐liquid‐solid (VLS) grown silicon nanowires (SiNWs), can pave the way to achieving excellent flexibility and a high power‐to‐weight ratio (PTWR). Thanks to their vertical‐standing geometry, SiNWs framework can enhance the mechanical stability of RJ units, by keeping the working region far away from the stress‐rich substrate surface. Using low‐melting‐point metals as catalysts, the SiNW array can be fabricated at a low temperature down to 350 °C in a PECVD system, making it possible to directly construct robust RJ units on flexible, low‐cost substrates, such as Al foil. In this review, the recent progress of the flexible RJ a‐Si:H thin film solar cells/photodetectors that are directly fabricated on the surface of low‐cost flexible substrates is reviewed. Moreover, these RJ flexible optoelectronics are demonstrated for use in wearable and real‐time health monitoring, and as cardiac pacemakers for heart stimulation. This RJ technology highlights a promising potential to establish high‐performance, low‐cost, mechanically stable flexible optoelectronic for wearable, portable applications.

Nonradiative Energy Transfer Enables a hv < Eg Response of Perovskite Quantum Dots in Si-Based Inorganic–Organic Hybrid Solar Cells

“…Nowadays, crystalline silicon (c-Si) based solar cells dominate ∼95% of the photovoltaic (PV) market . So, even an insignificant performance improvement of these commercial c-Si solar cells, to seek a more competitive levelized cost of electricity (LCOE), is highly valuable. − Until now, a bunch of strategies have been demonstrated, such as constructing different stacked tandem even multijunction cell architecture (perovskite/c-Si tandem, − polymer/perovskite tandem, − or amorphous Si/c-Si tandem, − and so on), to overcome the Shockley-Queisser limit of ∼33% for single-junction c-Si solar cells . For example, the perovskite thin film materials, attractive in recent years for their high spectral response, and low cost as well as a high initial performance of a single junction, − can be used as the top cell, to form perovskite/Si tandem solar cells. , However, there are lots of challenges in designing/fabricating tandem/multijunction, such as photocurrent matching, tunnel junction, and so on. , Besides, the high-energy photons, particularly in the ultraviolet (UV) wavelength region, which have energy much higher than the bandgap, are mostly absorbed nearly at the surface of Si devices but provide few effective carriers for device performance because of more defect states at the interface .…”