10:45 〜 11:15
▲ [10a-N305-6] Carrier Multiplication in Dual-gate p-n Junction of MoTe2 Film
キーワード：Carrier multiplication, 2D materials, Photovoltaics
A major challenge to improve solar energy conversion lies in the efficient use of the excess energy of photoexcited hot carriers. In general, the single-photon absorption in a semiconductor produces one electron-hole pair while the photon energy above the energy gap is dissipated as heat by phonon emission. This limits a maximum power conversion efficiency of a single junction solar cell of ~33%, known as the Shockley-Queisser limit. To break this threshold and boost the efficiency of solar cells, carrier multiplication (CM) has been suggested as a potential approach but has yet to be proven relevant to practical devices. We suggest 2D materials as a solution to this issue and believe that the observation of CM in 2D materials will be a breakthrough within the field of 2D research. In this talk, I will present a demonstration of the CM effect through simple photocurrent measurements by fabricating the dual-gate p–n junction of a MoTe2 film on a transparent substrate. The photocurrent was elevated proportionately to the excitation photon energy. The boosted quantum efficiency confirms the multiple electron-hole pair generation of >2Eg, consistent with CM results from an optical approach, pushing the solar cell efficiency beyond the Shockley–Queisser limit.