Fabrication of CIS Absorber Layers with Different Thicknesses Using A Non-Vacuum Spray Coating Method.

Chien-Chen Diao,Yen-Lin Chen,Hsin-Hui Kuo,Cheng-Fu Yang,Wen-Cheng Tzou

doi:10.3390/ma7010206

Abstract

In this study, a new thin-film deposition process, spray coating method (SPM), was investigated to deposit the high-densified CuInSe2 absorber layers. The spray coating method developed in this study was a non-vacuum process, based on dispersed nano-scale CuInSe2 precursor and could offer a simple, inexpensive, and alternative formation technology for CuInSe2 absorber layers. After spraying on Mo/glass substrates, the CuInSe2 thin films were annealed at 550 °C by changing the annealing time from 5 min to 30 min in a selenization furnace, using N2 as atmosphere. When the CuInSe2 thin films were annealed, without extra Se or H2Se gas used as the compensation source during the annealing process. The aim of this project was to investigate the influence of annealing time on the densification and crystallization of the CuInSe2 absorber layers to optimize the quality for cost effective solar cell production. The thickness of the CuInSe2 absorber layers could be controlled as the volume of used dispersed CuInSe2-isopropyl alcohol solution was controlled. In this work, X-ray diffraction patterns, field emission scanning electron microscopy, and Hall parameter measurements were performed in order to verify the quality of the CuInSe2 absorber layers obtained by the Spray Coating Method.

Highlights

CuInSe2 and Cu(In,Ga)Se2 (CIGS) are two of the most promising materials for thin film photovoltaic devices as they have an appropriate direct band gap and high absorption coefficient in the visible and near-infrared lights, and, therewith, low layer thickness required for light absorption
As 0.05 mL isopropyl alcohol (IPA)/CIS composite was used, the maximum texture coefficient (TC) value of (112) plane was revealed at 10-min-annealed CIS absorber layers; as 0.1 mL
IPA/CIS composite was used, the maximum TC value of (112) plane of the CIS absorber layers had no apparent trend as annealing time was increased

Summary

Introduction

CuInSe2 (abbreviates as CIS) and Cu(In,Ga)Se2 (CIGS) are two of the most promising materials for thin film photovoltaic devices as they have an appropriate direct band gap and high absorption coefficient in the visible and near-infrared lights, and, therewith, low layer thickness required for light absorption. Many different manufacturing processes have been developed to fabricate the CIS and CIGS absorber layers [2,3], and, far, the two-stage method is the cheapest and easiest to perform on an industrial scale [4]. For a two-stage method, the compositional uniformity and surface morphology of metallic precursors affect the quality of the absorber layers. To ensure the compositional uniformity of absorber layers, many procedures using metal or alloy thin films, with differently stacked Cu-In and Cu-In-Ga structures, have been proposed [5,6]. In addition to the two-stage growth processes, sputtering and co-evaporation are two of the most popular vacuum methods to deposit CIS and CIGS absorber layers. Shi et al used one-step sputtering of a single quaternary CIGS chalcogenide target at room temperature to fabricate the CIGS thin films

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