1/5/2023 0 Comments Three thin film solarcell![]() Also deposition of a thin layer of low band-gap Sb 2Te 3 or copper alloy at surface “A” shown in Figure 1.68 helps to form an Ohmic contact on CdTe. Often an etch of phosphoric acid (H 3PO 4) and HNO 3 or bromide-methanol is used to remove CdCl 2 salt resulting from the activation step. Next, an activation heat treatment is required in the presence of CdCl 2 vapor at about 400☌ irrespective of the deposition method. Both CdS and CdTe can be deposited using CSS between 550☌ and 600☌. A 3–10 µm thick absorber CdTe layer is typically deposited by CSS, but sputtering, electrodeposition and spray pyrolysis can also be used. In the next step, the CdS buffer layer is deposited either by closed space sublimation (CSS) or chemical bath deposition (CBD). For superstrate construction, where the absorption layer is directly deposited on the front contact layer, commercially available FTO coated glass substrate is used for solar cell manufacturing.Īs shown in Figure 1.71, after substrate inspection a TCO layer is sputter deposited on the glass substrate. ![]() For CdTe and a-Si cells, with absorption edge below 900 nm, fluorine-doped tin oxide, FTO (SnO 2:F), or indium-tin-oxide (ITO), is a suitable choice. The choice of a TCO also depends on the absorption edge of the thin film cell. These requirements are fulfilled by transparent conducting oxides (TCOs). Haze describes the ability of a layer to trap light. Adequate conductivity, transparency to light and haze are some of the important property requirements for front contact layers. For CdTe solar cells, typically borosilicate glass substrate for high temperature (up to 600☌) processing and soda-lime glass substrate for low temperature (60–500☌) processing are used.Īs shown in Figure 1.68, all three types of thin film solar cells require front and back contacts that are usually sputter deposited. If Na-free substrate is used, an Na precursor such as Na 2Se, Na 2S or NaF is incorporated on the substrate surface during device fabrication. Sodium (Na) containing soda-lime glass substrate is used in CIGS solar cell, because it improves cell efficiency. For thin film solar cell that requires high temperature processing of thin films, suitable glass or ceramic substrate is used. Substrate (glass, metal, polymer) of a solar cell is a passive component, but it may play an important role in determining the efficiency of the cell. The most common device junctions in thin film solar cells are CdTe, CIGS and a-Si based.įigure 1.68(a–c) show typical constructions of CdTe, CIGS and a-Si thin film solar cells. Although the solar cells appear to be a simple junction device in which two electronically dissimilar materials are separated by an electronic barrier to separate charges, process parameters for thin film deposition greatly affect the device performance. Thin film solar cells are promising because of the scope of device design in terms of junction formation, substrate types, substrate size and tailored performance. ![]() Jaydeep Sarkar, in Sputtering Materials for VLSI and Thin Film Devices, 2014 1.7.2 Thin film solar cells Key deposition and growth techniques and challenges are also reported in this chapter. An attempt has been made to report on the developments into thin film materials and the efficiencies achieved. However, the main challenges for thin film technologies, including perovskite solar cells, are their stability and toxicity involved in the manufacturing process. The efficiency increase in perovskite solar cells has significantly increased the potential thin film PVs, to become a low cost alternative for commercially available solar cell technologies. ![]() The increase in the efficiency of thin film solar cells and perovskite into 23% mark has created significant attention in the photovoltaic market, particularly in the integrated photovoltaic (BIPV) field. ![]() Thin film solar cell technology has recently seen some radical advancement as a result of new materials and innovations in device structures. Hari Upadhyaya, in A Comprehensive Guide to Solar Energy Systems, 2018 Abstract ![]()
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