Lab to Large Scale Transition for Non-Vacuum Thin Film CIGS Solar Cells: Phase I Annual Technical Report, 1 August 2002-31 July 2003

A High‐Efficiency Solution‐Deposited Thin‐Film Photovoltaic Device

“…[9][10][11][12] Several solution-based approaches have also been reported, including (with best power conversion efficiencies achieved) electrochemical deposition (7% for all elements deposited at once, 9% for deposition of metals followed by a separate hightemperature selenization step), [13][14][15] spray pyrolysis/spray chemical vapor deposition (CVD) ( 5%), [16,17] and nanoparticle-precursor deposition (14%). [18][19][20] Limitations of previously reported solution-based CIGS deposition approaches include: (i) incorporation of carbon, oxygen, and other impurities from the precursors or starting solutions; (ii) the need for multistep processing (e.g., a typical nanoparticle process involves making metal oxide nanoparticles, depositing the oxides as films, reducing the films to metals using a hightemperature reduction step, followed by high-temperature selenization); [19,20] (iii) the requirement for a high-temperature selenization/sulfurization step using toxic gases (e.g., H 2 Se) and/or a post-deposition cyanide-bath etch to achieve adequate grain growth and improve phase purity; and (iv) difficulty incorporating dopants such as Ga in a uniform and controllable fashion. While commercial production of CIGS modules has recently commenced, attaining reproducible, homogeneous and appropriately tailored CIGS films over large areas continues to pose a daunting hurdle for the development of pervasive cost-competitive PV technology.…”

Direct Liquid Coating of Chalcopyrite Light‐Absorbing Layers for Photovoltaic Devices

“…Nanoparticle oxide suspensions have been used for the deposition of very successful devices, [90][91][92][93][94] reaching efficiencies of 13.6 %. [91] In one of the more completely described methods, [92] the powders were prepared by precipitation of aqueous metal salt solutions via hydroxide addition, followed by heat treatment of the obtained powders.…”

“…Ga-incor- Oxides allow air anneal to burn out residual difficulty to remove oxygen completely from final suspension, 13.6 % [91] carbon from additives film Metals similarity to standard sequential vachigh tendency to alloy and aggregate, possible phase suspension, 10 % [90] uum processes segregation Salts off-the-shelf chemicals and multiple op-difficulty to form high quality layers due to crystalli-solution, 6.7 % [87] tions for choice of salt zation of precursor layer and impurities from salt Metalallow the formation of metallic laycarbon and/or oxygen contamination in final film; solution, 9 % [88] organics ers [88] or reactive amorphous oxides [78] low critical thickness per layer poration and desirable grading was achieved through subsequent in-diffusion of a gallium compound. [94] Solution-based (as opposed to nanoparticle or suspension based) approaches leading to in-situ formation of oxide precursor films have also been developed. Soft chemistry methods, often referred to as "sol-gel" offer an ample choice of solvents and additives and allow the formation of stable solutions that do not segregate upon drying.…”

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

“…Second, low temperature processing is critical when using polymer‐based substrates such as polyimide. Currently the two major types of flexible substrates used for CIGS solar cells are metal foils including stainless steel,70 titanium,71, 72 zirconium,72 copper,73 molybdenum,74 and plastics such as polyimide 74, 75. Metal foil‐based devices generally outperform those fabricated on polyimide, as typical evaporation‐based deposition processes function best at temperatures around 600 °C,2, 5 which polymer‐based substrates cannot survive.…”