ˈiːvən ðˌoʊ ðə ɹˈɛkɚdhˈaɪ ɪfˈɪʃənsi ɪz mˈoʊst lˈaɪkli dˈuː tə lˈoʊ θˈɜːməl kɑːndəktˈɪvᵻɾi ʌvðə kɹˈɪstəl, ðɪ ᵻlɛktɹˈɑːnɪk stɹˈʌktʃɚ mˌeɪhɐv æz ɪmpˈoːɹtənt ɹˈoʊl: ˌɛsˈɛn sˈiː hɐz hˈaɪli ˌænɪsətɹˈɑːpɪk vˈeɪləns bˈænd stɹˈʌktʃɚ, wˌɪtʃ kənsˈɪsts ʌv mˌʌltɪpəl vˈælɪz ðæt ˈækt æz ˌɪndᵻpˈɛndənt tʃˈænəlz fɔːɹ vˈɛɹi mˈoʊbəl, lˈoʊ ɪfˈɛktɪvmˈæs tʃˈɑːɹdʒ tɹˈænspoːɹt wɪðˈɪn, ænd hˈɛvikˈæɹiɚ kɑːndəktˈɪvᵻɾi pˌɜːpəndˈɪkjʊlɚ tə ðə lˈeɪɚz.
Even though the record-high efficiency is most likely due to low thermal conductivity of the crystal, the electronic structure may have as important role: SnSe has highly anisotropic valence band structure, which consists of multiple valleys that act as independent channels for very mobile, low effective-mass charge transport within, and heavy-carrier conductivity perpendicular to the layers.