Spray Ion Layer Gas Reaction (ILGAR®) – The Alternative Buffer for Thin-Film Solar Cells on Glass or Foils (CIS or CdTe)
The standard buffer layer in a chalcopyrite thin film solar cell is made by chemical bath deposition (CBD). This is a reliable and commercially accepted method. However it also has a number of disadvantages such as: long process times, large amounts of liquid waste, critical process parameters, an inherent batch type nature and difficulties with very large substrates. As the size of the substrates used in thin film production increases and the tact time decreases there is a request for new methods with the buffer layer deposition as one example.
In a collaboration between Helmholtz-Zentrum Berlin für Materialien und Energie (HZB), formerly the Hahn-Meitner-Institut (HMI), and SINGULUS, an alternative buffer layer deposition technique has been developed for thin film solar cell fabrication. The socalled Ion-Layer-Gas-Reaction Process (ILGAR®) offers a new, cost efficient, chemical method to manufacture a thin homogeneous In2S3 layer (20 nm), as an alternative to the common CdS-buffers.
The Spray-ILGAR® deposited indium sulfide buffer layers are capable to replace the cadmium sulfide buffers used in chalcopyrite cells in order to avoid the toxic cadmium. First 30x30 mini-modules on a Pilotline Cu(In,Ga)(S,Se)2 absorbers achieved an efficiency of 13.0 % after light soaking. The nature of the spray technique ensures that the ILGAR® process is reproducible, fast, cheap and suitable for scaling up into an in-line process on large area substrates.
Process Chambers of the ILGAR® Lab System: