Quadruple-band synglisis enables high thermoelectric efficiency in earth-abundant tin sulfide crystals Thermoelectrics have been limited by the scarcity of their constituent elements, especially telluride. The earth-abundant, wide-bandgap ( E g ≈ 46 k B T ) tin sulfide (SnS) has shown promising performance in its crystal form. We improved the thermoelectric efficiency in SnS crystals by promoting the convergence of energy and momentum of four valance bands, termed quadruple-band synglisis. We i...