Nanostructure of Porous Si and Anodic SiO2 Surface Passivation for Improved Efficiency Porous Si Solar Cells

Abstract

The photovoltaic effect in the anodic formation of silicon dioxide (SiO2) on porous silicon (PS) surfaces was investigated toward developing a potential passivation technique to achieve high efficiency nanostructured Si solar cells. The PS layers were prepared by electrochemical anodization in hydrofluoric acid (HF) containing electrolyte. An anodic SiO2 layer was formed on the PS surface via a bottom-up anodization mechanism in HCl/H2O solution at room temperature. The thickness of the oxide layer for surface passivation was precisely controlled by adjusting the anodizing current density and the passivation time, for optimal oxidation on the PS layer while maintaining its original nanostructure. HRTEM characterization of the microstructure of the PS layer confirms an atomic lattice matching at the PS/Si interface. The dependence of photovoltaic performance, series resistance, and shunt resistance on passivation time was examined. Due to sufficient passivation on the PS surface, a sample with anodization duration of 30 s achieved the best conversion efficiency of 10.7%. The external quantum efficiency (EQE) and internal quantum efficiency (IQE) indicate a significant decrease in reflectivity due to the PS anti-reflection property and indicate superior performance due to SiO2 surface passivation. In conclusion, the surface of PS solar cells could be successfully passivated by electrochemical anodization.

Enhanced Photoluminescence of Electrodeposited Europium Complex on Bare and Terpyridine-Functionalized Porous Si Surfaces

“…The properties have consequently been determined by the finally achieved pore sizes and depths. The application areas are very wide, and include sensors, catalysts, solar cells, and charge storages [8][9][10][11][12][13][14][15][16][17]. For sensors, Ramírez-González et al controlled the thickness of the PS layer and tested ethanol-sensing performance by measuring conductivity.…”

“…They demonstrated that the nanocomposites showed an excellent catalytic performance for the reduction of 4-nitrophenol to 4-aminophenol by NaBH 4 . For solar cells, Sundarapura et al prepared an anodic SiO 2 layer on a PS surface, and demonstrated that the solar-cell efficiency was significantly improved [13]. For energy storage, Ortaboy et al synthesized MnO x -decorated carbonized porous Si nanowire, and showed that the PS nanowire-based pseudocapacitor electrode had a specific capacitance of 635 F g −1 ,…”

Incorporation of Ions into Nanostructured Anodic Oxides—Mechanism and Functionalities

“…Anodization is a commonly used name for electrochemical oxidation of metals [1][2][3], their alloys [4,5] and semiconductors [6][7][8] under either galvanostatic or potentiostatic conditions in a two-electrode setup since the oxidized material plays a role of an anode. Originally, the major application of anodic oxidation was corrosion protection of lightweight aluminum alloys [9,10].…”

Improvement of Corrosion Resistance of Stainless Steel Welded Joint Using a Nanostructured Oxide Layer

“…Results show that the anodization process coupled with the heat treatment provides significant corrosion protection to the SS and the welds. Furthermore, the proposed methodology has distinct advantages of being simple, safe, low-cost, and versatile, making it highly promising in numerous fields [33][34][35].…”