Enhanced Photovoltaic Characteristics of Screen-Printed Monocrystalline Silicon Solar Cells by Rear Electroplated Copper

Abstract

Improved photovoltaic characteristics for screen-printed monocrystalline silicon solar cells (SPSSCs) were demonstrated by electroplated copper (EPC) as the rear metallization. The Al back-surface-field (Al-BSF) formed by screen-printed (SP) Al paste was prepared as a seed layer for the EPC. The EPC parameters, including the current density, electroplating time, buffered-oxide-etch (BOE), and mixed HF/HNO3/H2O pretreatments, were investigated. The experimental results indicate that the relatively higher intensity from the Cu (111) plane and the Cu (200) plane was demonstrated to be approximately 2.2 for the EPC at a current density of 25 mA/cm2. Excellent adhesion of up to 2.4 N/mm was demonstrated. The achievement of a conversion efficiency (CE) improvement of more than 1.8%, from 15.4% to 17.2% for SPSSCs with EPC as the rear contact, was determined. The enhancement could be attributed to the reduction of the series resistance (SR) and an increase in the adhesion between the Al-BSF and EPC.

Photovoltaic and Physical Characteristics of Screen-Printed Monocrystalline Silicon Solar Cells with Laser Doping and Electroplated Copper

“…Furthermore, a thicker EPC contact layer was formed up to 50 min, as shown in Figure 11(d). A thicker EPC contact layer was demonstrated at a high EPC time resulting in a large series resistance [13]. Moreover, an excellent resistivity caused by the Cu crystal orientation of (111) was demonstrated for the EPC formed at a current density of 25 mA/cm 2 [13].…”

“…A thicker EPC contact layer was demonstrated at a high EPC time resulting in a large series resistance [13]. Moreover, an excellent resistivity caused by the Cu crystal orientation of (111) was demonstrated for the EPC formed at a current density of 25 mA/cm 2 [13]. The reason can be attributed to the (111)-oriented copper film with no slip line [24].…”

“…Furthermore, compared with the SPMSCs with a screen-printed Al rear, the achievement of a conversion efficiency improvement of more than 1.5% 5 International Journal of Photoenergy absolute from 16.2% to 17.7% for SPMSCs with a laser pinhole process was demonstrated. One method to evaluate the series resistance from a solar cell is to find the slope of the J-V curve at the open-circuit voltage point [13]. The series resistances of 0.4 and 0.6 Ω·cm 2 for SPMSCs with EPC and screen-printed Al as the rear contacts, respectively, were demonstrated.…”

“…Improved photovoltaic characteristics for SPMSCs were demonstrated by EPC as the rear metallization. The seed layer for EPC was achieved by an Al back surface field formed by a screen-printed Al paste [13]. In this work, a B-BSF seed layer for EPC will be demonstrated.…”