講演情報
[18a-PB1-13]Temperature-Programmable Bulk Photovoltaic Effect in Ionic Intramolecular Charge Transfer Complexes
〇Gurvan Bosser1,4, Justin Llandro1,3, Naoki Ogawa1,4, Masao Nakamura4,5,1, Yoshinori Tokura4,6, Satoshi Okamoto1,2,3 (1.RIKEN BZT, 2.Inst. Sci. Tokyo, 3.Sumitomo Chem., 4.RIKEN CEMS, 5.Tohoku Univ., 6.Univ. of Tokyo)
キーワード：
shift current、bulk photovoltaic effect
The bulk photovoltaic effect (BPVE), dominated by shift current, is of strong interest due to its potential to exceed the Shockley–Queisser limit of conventional solar cells. Here, we investigate organic nonlinear optical (NLO) crystals, commonly used for terahertz generation, in which shift current has not previously been reported. We demonstrate the first experimental observation of shift current in ionic intramolecular charge-transfer complexes, including 4-N,N-dimethylamino-4′-N′-methylstilbazolium tosylate (DAST) and related derivatives. The zero-bias photocurrent exhibits an unexpected exponential increase with temperature, in contrast to conventional shift-current behavior typically enhanced at low temperatures. This anomalous trend is attributed to thermal activation of carriers initially trapped by ionic bonding within the crystal lattice. In comparison, non-ionic NLO analogues show neither detectable shift current nor temperature dependence, highlighting the key role of cation–anion interactions in enabling bulk charge transport in non-centrosymmetric lattices.