NOVELTY - An absorber layer of photovoltaic device is fabricated by forming an absorber layer (106) on flexible foil or aluminum substrate (102), adding stiffening layer to backside of the substrate, and rapidly heating the nascent absorber layer and/or substrate from an ambient temperature to a plateau temperature of 200-600 degrees C at temperature increasing rate of 5-150 degrees C/sec; maintaining the absorber layer and/or substrate in the plateau temperature range for 2-30 minutes; and reducing the temperature of the absorber layer and/or substrate.    USE - Method for fabricating an absorber layer of photovoltaic device.    ADVANTAGE - The method utilizes aluminum substrates which are much cheaper and more lightweight than conventional substrate, thus solar cells based on aluminum substrates can have lower cost per watt for electricity generated and far shorter energy payback period when compared to conventional silicon-based solar cells. The substrate permits both high throughput roll-to-roll printing during solar cell fabrication and faster and easier installation process during solar module and system installation. The method allows for fabrication of lightweight and inexpensive photovoltaic devices on aluminum substrate. The rapid heating allows for proper annealing and incorporation of group VIA elements without damaging or destroying the aluminum foil substrate.    DETAILED DESCRIPTION - Group VIA elements are incorporated into the absorber layer before or during the step rapidly heating the absorber layer and/or substrate. The step of rapidly heating is performed by radiant heating using infrared lamps. A layer of molybdenum is disposed between the substrate and absorber layer. An intermediate layer may be incorporated between aluminum substrate and layer of molybdenum to inhibit inter-diffusion of molybdenum and aluminum during rapid heating. An INDEPENDENT CLAIM is included for a photovoltaic device, comprising substrate and absorber layer.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional schematic diagram of the fabrication of absorber layer.    Substrate (102)    Barrier layer (103)    Base electrode (104)    Absorber layer (106)    Rapid heating unit (110)