Solution growth of chalcopyrite Cu(In1−x Ga x )Se2 single crystals for high open-circuit voltage photovoltaic device

Akira Nagaoka,Kensuke Nishioka,Kenji Yoshino,Taizo Masuda,Yusuke Shigeeda

doi:10.1515/htmp-2021-0047

Abstract

Abstract I–III–VI2 Chalcopyrite Cu(In1−x Ga x )Se2 (CIGS) has attracted attention as absorbing layer in photovoltaic (PV) device. In this study, we investigated the fundamental properties of CIGS single crystals, and fabricated single crystal-based PV device. CIGS single crystals without secondary phase were successfully grown by In-solvent traveling heater method (THM). The conversion of conduction type from n- to p-type can be observed above 0.3 of Ga ratio x because of high acceptor defect concentration. PV device based on high-quality CIGS bulk single crystal demonstrates high open-circuit voltage of 0.765 V with the efficiency of 12.6%.

Highlights

The I–III–VI2 chalcopyrite compounds have received much attention due to its various energy application over the past few decades
The powder X-ray diffraction (XRD) patterns of CIGS single crystal at 300 K are shown in Figure 2, and exhibit major peaks corresponding to diffraction lines of the chalcopyrite structure of CIGS (ICDD data # 00-040-1487 CuInSe2 and ICDD data #00-035-1102 CuIn0.5Ga0.5Se2)
We have experimentally studied the growth and basic properties of Cu(In1−xGax)Se2 (x = 0–0.5) single crystal for higher efficiency PV device

Summary

Introduction

The I–III–VI2 chalcopyrite compounds have received much attention due to its various energy application over the past few decades. Cu(In1−xGax)Se2 (CIGS) have been well known for its potential in the development of high-efficiency and low-cost photovoltaic (PV) device. Solar Frontier (Idemitsu Kosan) demonstrated a polycrystalline thin-film PV device with the highest conversion efficiency of 23.35% [1]. The commercial modules have already offered stable conversion efficiencies in the range of 17–19% [2]. It is difficult to obtain higher efficiency on a module scale due to the difficulty in controlling the manufacturing process on large area substrate. Wide bandgap I–III–VI2 chalcopyrite compounds have been the focus of intense study for developing wide-gap top cells in tandem structure cells

Methods

Results

Conclusion