Photovoltaic cell

An organic thin film transistor comprising:

• a gate electrode;
• a source electrode;
• a drain electrode;
• and
• an active layer;
• wherein the active layer contains a macromolecular compound having a structural unit represented by Formula (1) or Formula (2):
• wherein R50 and R51 are the same as or different from each other and represent a hydrogen atom, a halogen atom, or a monovalent organic group,
• and further having a structural unit represented by Formula (3) or Formula (4):
• wherein Rs are the same as or different from each other and represent a hydrogen atom or a substituent, or are bonded with each other to form a ring, wherein the substituent is selected from a group consisting of an alkyl group, an alkyloxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, an arylalkyl group, an arylalkyloxy group, an arylalkylthio group, an arylalkenyl group, an arylalkynyl group, an amino group, a substituted amino group, a silyl group, a substituted silyl group, a halogen atom, an acyl group, an acyloxy group, an amido group, a monovalent heterocyclic group, a carboxyl group, a substituted carboxyl group, a nitro group, and a cyano group, wherein a hydrogen atom contained in the substituent is optionally substituted with a fluorine atom,
• wherein an inverse of excitation energy of the macromolecular compound from a ground singlet state to a lowest excited singlet state that is calculated using a time-dependent density functional theory is 0.43 (eV−1) or more.

A method of calculating excitation energy of a macromolecular compound comprising a repeated unit represented by Formula (2) from a ground singlet state to a lowest excited singlet state, the method comprising:

• calculating, using a processor, excitation energy of a compound represented by Formula (2-1), excitation energy of a compound represented by Formula (2-2), and excitation energy of a compound represented by Formula (2-3) by a time-dependent density functional theory;
• plotting, on a coordinate plane in which a value represented by 1/k is assigned on an abscissa axis when number of aromatic rings contained in a main chain of the compound is assumed to be k and excitation energy is assigned on an ordinate axis, a first point of which abscissa is a value represented by 1/k for the compound represented by Formula (2-1) and of which ordinate is the excitation energy of the compound represented by Formula (2-1), a second point of which abscissa is a value represented by 1/k for the compound represented by Formula (2-2) and of which ordinate is the excitation energy of the compound represented by Formula (2-2), and a third point of which abscissa is a value represented by 1/k for the compound represented by Formula (2-3) and of which ordinate is the excitation energy of the compound represented by Formula (2-3);
• calculating an approximate straight line that connects the first point, the second point, and the third point by least-squares method;
• and
• calculating an ordinate of an intersection point of a straight line on which the value represented by 1/k is 0 with the approximate straight line on the coordinate plane, as the excitation energy of the macromolecular compound;
• wherein Formulae (2), (2-1), (2-2) and (2-3) are as follows:
• —Ar3— (2)
• H—Ar3—H (2-1)
• H—Ar3—Ar3—H (2-2)
• H—Ar3—Ar3—Ar3—H (2-3)
• wherein Formula (2) represents a divalent organic group comprising one or a plurality of structure units represented by Formula (1);
• wherein H represents a hydrogen atom;
• and when Ar3 is plurally present, Ar3s may be the same as or different from each other,
• wherein Formula (1) is as follows:
• wherein Ar1 and Ar2 are the same as or different from each other and represent a trivalent aromatic hydrocarbon group or a trivalent heterocyclic group;
• X1 and X2 are the same as or different from each other and represent —O—, —S—, —C(═O)—, —S(═O)—, —SO2—, —C(R50)(R51)—, —Si(R3)(R4)—, —N(R5)—, —B(R6)—, —P(R7)—, or —P(═O)(R8)—;
• R50, R51, R3, R4, R5, R6, R7, and R8 are the same as or different from each other and represent a hydrogen atom, a halogen atom, or a monovalent organic group;
• and X1 and Ar2 are bonded with atoms adjacent to each other on a ring that constitutes Ar1, and X2 and Ar1 are bonded with atoms adjacent to each other on a ring that constitutes Ar2.