Mie Resonance-Modulated Spatial Distributions of Photogenerated Carriers in Poly(3-hexylthiophene-2,5-diyl)/Silicon Nanopillars

Abstract

Organic/silicon hybrid solar cells have great potential as low-cost, high-efficiency photovoltaic devices. The superior light trapping capability, mediated by the optical resonances, of the organic/silicon hybrid nanostructure-based cells enhances their optical performance. In this work, we fabricated Si nanopillar (NP) arrays coated with organic semiconductor, poly(3-hexylthiophene-2,5-diyl), layers. Experimental and calculated optical properties of the samples showed that Mie-resonance strongly concentrated incoming light in the NPs. Spatial mapping of surface photovoltage, i.e., changes in the surface potential under illumination, using Kelvin probe force microscopy enabled us to visualize the local behavior of the photogenerated carriers in our samples. Under red light, surface photovoltage was much larger (63 meV) on the top surface of a NP than on a planar sample (13 meV), which demonstrated that the confined light in the NPs produced numerous carriers within the NPs. Since the silicon NPs provide pathways for efficient carrier transportation, high collection probability of the photogenerated carriers near the NPs can be expected. This suggests that the optical resonance in organic/silicon hybrid nanostructures benefits not only broad-band light trapping but also efficient carrier collection.

Band Alignment at Au/MoS2 Contacts: Thickness Dependence of Exfoliated Flakes

“…KPFM, a variant of AFM, enables the local V surf to be determined with a nanoscopic spatial resolution. 20 For comparison, two kinds of substrates were used: SiO 2 (300 nm)/Si wafers (hereafter, referred to as "SiO 2 ") and SiO 2 /Si wafers coated with Au(100 nm)/Ti(20 nm) thin films (hereafter, referred to as "Au"). The KPFM measurements were conducted in a glovebox filled with N 2 gas, as schematically illustrated in Figure 2.…”

“…SPV is the difference of V surf in the dark (V surf,dark ) and under light (V surf,light ): SPV = V surf,light − V surf,dark . 20 The SPV measurements were done using the KPFM system, and the light source was a green laser (wavelength of 525 nm) with an output power of 20 mW. SPV is almost zero for 1-MoS 2 , and larger SPV values appear for thicker MoS 2 layers.…”

Hybrid Silicon Nanowires for Solar Cell Applications

“…doping process [50]. In order to enhance the light-trapping efficiency, Si nanostructures such as nanopyramids [49] and nanowires [51] have been applied, leading to an increase in the short-circuit current density (J SC ).…”

Embedded Metal Electrode for Organic–Inorganic Hybrid Nanowire Solar Cells

“…As a platform for cost-effective crystalline Si (c-Si) solar cells, an organic–inorganic hybrid structure has been proposed to replace the conventional p–n junction. The hybrid structure is composed of a transparent conducting polymer and c-Si. − A Schottky junction at the conducting polymer/c-Si interface can easily be created using a simple spin-coating process at room temperature, while a conventional Si p–n junction is formed via a high-temperature doping process. ,, The Schottky junction allows the device to function as a solar cell despite the absence of a thermally formed p–n junction. This is because an energy barrier induced by the work function difference between the conducting polymer and c-Si can efficiently separate photogenerated carriers.…”

“…In order to enhance the light-trapping efficiency, Si nanostructures such as nanopyramids, ,, nanotubes, nanoholes, and nanowires ,,− ,, have been applied, leading to an increase in the short circuit current density ( J SC ). Jian et al .…”