NOVELTY - Forming an absorber layer of a photovoltaic device (100) involves forming a nascent absorber layer (106) containing at least one element of group IB and at least one element of group IIIA on an aluminum foil substrate (102) by solution deposition; and rapidly heating the nascent absorber layer and/or substrate from an ambient temperature to a plateau temperature (i.e. 200 - 600degreesC).    USE - For forming an absorber layer on aluminum foil substrate, to form a photovoltaic device (claimed).    ADVANTAGE - The aluminum substrates are cheaper and lightweight than conventional substrates. Thus, solar cell based on aluminum substrates can have a lower cost per watt for electricity generated and a shorter energy payback period when compared to conventional silicon-based solar cells. The aluminum substrates allow for a flexible form factor that permits both high-throughout roll-to-roll printing during solar cell fabrication and faster and easier installation processes during solar module and system installation. The method allows the fabrication of lightweight and inexpensive photovoltaic devices on aluminum substrates. The flash-heating/rapid thermal processing of the nascent absorber layer allows for proper annealing and incorporation of group VIA elements without damaging or destroying the aluminum foil substrate. The use of aluminum foil substrates can greatly reduce the materials cost of photovoltaic devices, e.g. solar cells, made on such substrates thereby reducing the cost per watt. Economies of scale can be achieved by processing the aluminum foil substrate in a roll-to-roll fashion, with the various layers of the photovoltaic devices being built up on the substrate as it passes through a series of deposition annealing and other processing stages. The photovoltaic cell has an intermediate layer between aluminum foil substrate and molybdenum base electrode, that inhibits the inter-diffusion of molybdenum and aluminum during heating.    DETAILED DESCRIPTION - The method further involves maintaining the absorber layer and/or substrate in plateau temperature range for about 2 - 30 minutes; and reducing the temperature of the absorber layer and/or substrate; and incorporating at least one group VIA element into the nascent absorber layer either before or during the step of rapidly heating the nascent absorber and/or substrate. The aluminum foil substrate is made by metallizing a polymer foil substrate with aluminum or an aluminum-based alloy. The group VIA elements include selenium or sulfur.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional schematic diagram illustrating fabrication of an absorber layer.    aluminum foil substrate (102)    interfacial layer (103)    base electrode (104)    nascent absorber layer (106)    heating unit. (110)