ORGANIC THIN FILM SOLAR BATTERY

PROBLEM TO BE SOLVED: To make the number of photons absorbed in large part of a mixed layer (e.g., a 90% region in thickness direction of the layer) almost constant in the thickness direction of the layer and the density of generated excitons almost constant in the thickness direction of the layer, thereby restraining deactivation caused by recombination of carriers to heighten the efficiency and extend the life of power generation.SOLUTION: An organic thin film solar battery includes a power generation layer between a pair of electrodes. A mixed layer included in the power generation layer is composed of a plurality of layers, each containing a p-type material and an n-type material. In a layer closest to the light incident side of the mixed layer, a weight ratio of the p-type material to the sum total in weight of the p-type and the n-type materials included in the layer is 30% or less. Furthermore, the weight ratio of the p-type material in each layer of the mixed layer is set so that, when light in a visible light included wavelength range enters upon the mixed layer via one of the electrodes, the number of photons absorbed by each layer in a region of up to 90% in layer thickness from the light incident side of the mixed layer is within a range of ±25% of the number of photons absorbed by the layer closest to the light incident side.