GaAs nanowire array solar cells with axial p-i-n junctions.
Because of unique structural, optical, and electrical properties, solar cells based on semiconductor nanowires are a rapidly evolving scientific enterprise. Various approaches employing III-V nanowires have emerged, among which GaAs, especially, is under intense research and development. Most reported GaAs nanowire solar cells form p-n junctions in the radial direction; however, nanowires using axial junction may enable the attainment of high open circuit voltage (Voc) and integration into multijunction solar cells. Here, we report GaAs nanowire solar cells with axial p-i-n junctions that achieve 7.58% efficiency. Simulations show that axial junctions are more tolerant to doping variation than radial junctions and lead to higher Voc under certain conditions. We further study the effect of wire diameter and junction depth using electrical characterization and cathodoluminescence. The results show that large diameter and shallow junctions are essential for a high extraction efficiency. Our approach opens up great opportunity for future low-cost, high-efficiency photovoltaics.
Ming Hsieh Department of Electrical Engineering and Center for Energy Nanoscience, University of Southern California , Los Angeles, California 90089, United States.
Maoqing
M
Yao
Ningfeng
N
Huang
Sen
S
Cong
Chun-Yung
CY
Chi
M Ashkan
MA
Seyedi
Yen-Ting
YT
Lin
Yu
Y
Cao
Michelle L
ML
Povinelli
P Daniel
PD
Dapkus
Chongwu
C
Zhou