TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The substrate is glass, ceramic, metal and/or polymer or metal coated glass. The precursor material comprises a member comprising Group I elements, Group II elements, Group III elements, Group IV elements and/or Group VI elements. The precursor vapor is Group I elements, Group II elements, Group III elements, Group IV elements and/or Group VI elements. The Group I elements are copper, silver and/or gold. The Group II elements are zinc and/or cadmium. The Group III elements are indium, gallium and/or aluminum. The Group IV elements are tin, germanium and/or silicon. The Group VI elements are selenium, sulfur and/or tellurium. The device further comprises at least one cooling chamber arranged in series, and means for conveying the precursor material from the series of at least one heating chamber through the series of at least one cooling chamber. In the device, each cooling chamber comprises means for supplying a precursor vapor at a desired partial pressure to a corresponding cooling chamber.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The method further comprises placing the precursor material on a substrate. The cooling step further comprises cooling the heated precursor material in the presence of the precursor vapor supplied at a partial pressure. The reaction temperature is at least 100 degrees C or 300-1000 (preferably 400-700) degrees C. In the method, preselected partial pressure of the precursor vapor is 1 mTorr-200 Torr, preferably 1-50 Torr. The cooling rate is at least 0.5 degrees C/second or 0.5-15 (preferably 1-5) degrees C/second. The method further comprises the step of preheating the precursor material to a preheating temperature. The step (b) further comprises transferring the precursor material to a first heating chamber (14) maintained at a first heating chamber temperature with the precursor vapor supplied at a first partial pressure, holding the precursor material in the first heating chamber for a first predetermined time, transferring the precursor material to a second heating chamber (16) maintained at a second heating chamber temperature with the precursor vapor supplied at a second partial pressure, and holding the precursor material in the second heating chamber for a second predetermined time. The step (c) further comprises transferring the heated precursor material to a first cooling chamber (18) containing the precursor vapor supplied at a preselected partial pressure, cooling the heated precursor material at a first cooling rate in the first cooling chamber to a temperature above ambient, transferring the heated precursor material to a second cooling chamber, and cooling the heated precursor material at a second cooling rate in the second cooling chamber to ambient. In the method: preselected partial pressure of the precursor vapor in the first cooling chamber is 1 mTorr-200 Torr, when the heated precursor material is 325-675 degrees C, preferably 0 mTorr-1 Torr, when the heated precursor material is at 0-325 degrees C. The time for maintaining the precursor material at the reaction temperature is 1 second-180 minutes, preferably 30 seconds-180 minutes. EXAMPLE - Precursor material containing copper, indium, gallium, and selenium was placed on a substrate composed of glass coated with a molybdenum film. The precursor material supported on the substrate was placed on a conveyor at the inlet of the device. The substrate with the precursor material was introduced through a gate valve into the preheat chamber, which was maintained at 100 degrees C. All of the chambers were maintained: at a background pressure of less than 1 mTorr; and any pressure increase mainly due to the selenium partial pressure produced by an external selenium gas source. The gate valves located on each side the chambers were maintain desired partial vacuum pressures and selenium partial pressures within the first and second heating chambers and the first cooling chamber. The gate valves only open for moving the substrate with the precursor material between corresponding adjacent chambers for further processing of the precursor material. The precursor material was heated to a preheat temperature of 100 degrees C after loading the substrate with the precursor material was placed into the preheat chamber and then the preheat chamber was pumped down to a partial vacuum pressure of 1 mTorr pressure prior to moving, where the substrate with the precursor material was placed into the first heating chamber. The first heating chamber maintains at a steady isothermic environment of 800 degrees C with an external selenium gas source supplying selenium gas at a partial pressure of 20 Torr. The substrate with the precursor material remains in the first heating chamber for 55 seconds after the gate valve between preheat chamber and the first heating chamber closes, where the precursor material was rapidly heated to a uniform temperature of 600 degrees C in the presence of the selenium gas to yield a reaction product. The reaction product was worked up to obtain a polycrystalline film of Group I, Group III and Group VI product produced by the reaction of the precursor vapor and the precursor material.