TECHNOLOGY FOCUS - POLYMERS - Preferred Compositions: Conjugated polymer block contains monomeric unit which has heterocyclic group, such as cyclopentadithiophene diyl group, dithienopyrrole diyl group, dithienosilol diyl group, dithienogermole diyl group, benzodithiophene diyl group, naphthodithiophene diyl group, thienothiophene diyl group, and/or thienopyrroledione diyl group. Conjugated polymer block contains a-b-containing monomeric unit in which bivalent heterocyclic group (b) has pi -conjugated skeleton different from the bivalent heterocyclic group (a) which consists of condensed pi -conjugated skeleton with a thiophen ring in a part of the chemical structure. Bivalent heterocyclic group (b) is dibenzosilole diyl group, dibenzogermole diyl group, dibenzofurandiyl group, carbazole diyl group, diketopyrrolopyrrole diyl group, benzothiadiazole diyl group, and/or benzotriazole diyl group. Conjugated polymer block has greater than or equal to 1 side chain e.g. optionally substituted alkyl group, alkoxy group, aryl group, heteroaryl group, alkyl carbonyl group, or alkyloxycarbonyl group. Conjugated polymer block contains side chain with carbon number of 3-20. Conjugated block copolymer contains greater than or equal to 1 polymer block consisting of monomeric unit which has side chain of linear structure and greater than or equal to 1 conjugated polymer block consisting of monomeric unit which has side chain of branched structure. Preferred Parameters: The value of eta of equation eta =CB x CD x LI (11), which evaluates the quality of the phase-separation structure of the photoelectric conversion active layer, is 4x 10 -3 in which CB is defined by equation (12) and CD is defined by equation (13) given in the document, where A total is the area of photoelectric conversion active layer region, H total is the length of film thickness direction of photoelectric conversion active layer region, NB is the total number of each region of the bright part domain in photoelectric conversion active layer, AB i is the i-th bright part of the domain, and HB i is the length of film thickness direction of the bright part of the i-th domain part, ND is the total number of each region of the dark part domain in photoelectric conversion layer, AD i is the i-th dark part of the domain, HD i is the length of film thickness direction of the dark part of the i-th domain part, and LI is defined by equation LI=l total/A total (14), where l total is the total length of the interface of a bright part domain and a dark part domain existing in the photoelectric conversion active layer region.