Fabrication and Photovoltaic Characteristics of Coaxial Silicon Nanowire Solar Cells Prepared by Wet Chemical Etching

Chien-Wei Liu,Chin-Lung Cheng,Bau-Tong Dai,Jun-Yuan Wang,Chi-Han Yang

doi:10.1155/2012/701809

Abstract

Nanostructured solar cells with coaxial p-n junction structures have strong potential to enhance the performances of the silicon-based solar cells. This study demonstrates a radial junction silicon nanowire (RJSNW) solar cell that was fabricated simply and at low cost using wet chemical etching. Experimental results reveal that the reflectance of the silicon nanowires (SNWs) declines as their length increases. The excellent light trapping was mainly associated with high aspect ratio of the SNW arrays. A conversion efficiency of ∼7.1% and an external quantum efficiency of ∼64.6% at 700 nm were demonstrated. Control of etching time and diffusion conditions holds great promise for the development of future RJSNW solar cells. Improving the electrode/RJSNW contact will promote the collection of carries in coaxial core-shell SNW array solar cells.

Highlights

Nanostructured solar cells with high efficiency and low cost are being considered to meet the urgent need for third-generation solar cell applications
Recent studies have shown that silicon nanowires (SNWs) that are prepared by the vapor-liquid-solid and wet chemical etching approaches can be employed to enhance the photovoltaic characterization because such SNW arrays have very low reflectance [1,2,3,4,5,6,7,8,9,10,11,12]
An improved conversion efficiencies (CEs) of approximately 7.1% with a Jsc of 27 mA/cm2, a Voc of 500 mV, and an fill factor (FF) of 52% was obtained for an radial junction silicon nanowire (RJSNW) array solar cell sample with a diffusion time of 3 hrs

Summary

Introduction

Nanostructured solar cells with high efficiency and low cost are being considered to meet the urgent need for third-generation solar cell applications. Theoretical studies have indicated that coaxial SNW structures with sub-5 nm p-n junction structures have potentiality to realize ultrahigh efficiencies due to the tunable energy bandgap [13]. The conversion efficiencies (CEs) of SNW solar cells are not yet large enough. SNW solar cells on metal foil with a current density of 1.6 mA/cm, an external quantum efficiency (EQE) of 12% at 690 nm, and a conversion efficiency of 0.1% have been described [5]. Radial junction SNW (RJSNW) solar cells with a Voc of 290 mV, a short-circuit current density (Jsc) of 4.28 mA/cm, and an FF of 33.0% have been demonstrated [7]. Etched SNW solar cells with a Jsc of 1.36 mA/cm and a Voc of 730 ± 20 mV have been proposed [17]. This study will scrutinize the etching time and the diffusion conditions of RJSNWs

Methods

Results

Conclusion