The thermoelectric effect was discovered in 1821 when Thomas Seebeck observed that a circuit made of two dissimilar metals, with junctions at two different temperatures, deflected a compass needle. However, in the ensuing nearly two-hundred years thermoelectric devices have failed to find use in any but niche applications. This slow progress, when compared to that of photo-voltaic devices which have greatly improved in roughly half the time, is due in large part to the contraindicated parameters which govern the efficiency of a thermoelectric material. Optimizing one parameter for thermoelectric performance often comes at the cost of hindering another, so multiple approaches must be used to improve the thermoelectric performance of a material. Therefore, material optimization requires a firm understanding of the underlying transport physics and materials science governing a material. When evaluating the viability of a material for thermoelectric use the dimensionless figure of merit, \textit{ZT}, is the standard metric. This dimensionless figure is a combination of the Seebeck coefficient and the electrical and thermal conductivities of the material, as well as the operating temperature, and is directly related to the efficiency of a thermoelectric generator. In the past 25 years the field of thermoelectricity has provided many materials with a \textit{ZT} in excess of unity, and recently materials have been reported with values greater than two. However, element toxicity, low elemental abundance, and complex synthesis techniques have prevented many of these materials from reaching commercial viability. This work presents a systematic study of the chalcopyrite family of semiconductors with chemical structure I-III-VI$_2$ where the group I element is copper. This family contains many possibilities for non-toxic, earth abundant materials which can be simply, and in some cases rapidly, synthesized. A better understanding of the physics governing the transport mechanisms in these materials could lead to their adoption in future thermoelectric applications, helping improve the energy efficiency of devices of all sizes.
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