The Development of Hydrazine‐Processed Cu(In,Ga)(Se,S)₂ Solar Cells

Abstract

The hydrazine-based deposition of Cu(In,Ga)(S,Se) 2 (CIGS) thin fi lms has attracted considerable attention in recent years due to its potential for the high-throughput production of photovoltaic devices based on this absorber material. This article provides an introduction as well as presenting a complete picture of the current status of hydrazine-based CIGS solar-cell fabrication, including the three major steps of this deposition process: dissolution of the precursor materials in hydrazine, deposition of a fi lm from the resulting precursor solution, and the completion and characterization of a photovoltaic device following absorber deposition. Recent discoveries are then discussed, regarding the dissolution chemistry of the relevant precursor complexes in hydrazine, which together represent the true foundation of this processing method. Recent studies on CIGS fi lm formation are then summarized, including the control and analysis of the crystalline phase, electronic bandgap, and fi lm morphology. Finally, the latest progress in high-performance device fabrication is highlighted, with a focus on optoelectronic characterization including current-voltage, junction capacitance, and minority carrier lifetime measurements. Finally, a discussion and future outlook is provided.

Surface Cleaning and Passivation Using (NH4)2S Treatment for Cu(In,Ga)Se2 Solar Cells: A Safe Alternative to KCN

“…[1][2][3][4][5] This material is of particular interest for use as an absorber layer in photovoltaic devices. [1][2][3][4][5] This material is of particular interest for use as an absorber layer in photovoltaic devices.…”

ZnO-Based Nanostructuring Strategy Using an Optimized Solution Process in CuInS2 Superstrate Photovoltaics

“…21,33 These phases are difficult to analyze based solely on XRD measurements because their peaks often overlap with those of the stoichiometric chalcopyrite CIS. For this reason, Raman spectroscopy is widely used to characterize the phase purity of CIS films.…”

Spray Pyrolysis of CuIn(S,Se)2 Thin Films Using Hydrazine-based Solutions

“…A clear colorless solution was formed after filtration and used immediately to avoid aggregate formation. For solutions (b) and (c), 0.5 M Cu 2 S-S hydrazine solution, 0.25 M In 2 Se 3 -Se hydrazine and 2 M Se hydrazine solution were prepared following procedures reported by others [3,5,6]. NOTE: due to the high toxicity of hydrazine, it should always be handled using precautions and proper protective equipment.…”

“…[3][4][5] Although this approach is applicable in most solution-based processes, concerns about the toxicity of hydrazine have limited it to small area spin coating of the absorber layer of photovoltaic devices. [6] Compared with spin coating, the spray deposition process has advantages including coating of arbitrarily large areas, capability to deposit on flexible and irregular shape surfaces, consistent control of substrate temperature, and continuity of processing. Early studies on spray pyrolysis deposition of CIGS films from metal salt based [7] and organometallic [8] precursors, resulted in absorber layers that achieved low efficiency due to incorporation of impurities and inhomogeneities in the films.…”