Jo Min-Kyung, Heo Hoseok, Lee Jung-Hoon, Choi Seungwook, Kim Ansoon, Jeong Han Beom, Jeong Hu Young, Yuk Jong Min, Eom Daejin, Jahng Junghoon, Lee Eun Seong, Jung In-Young, Cho Seong Rae, Kim Jeongtae, Cho Seorin, Kang Kibum, Song Seungwoo
Operando Methodology and Measurement Team, Interdisciplinary Materials Measurement Institute, Korea Research Institute of Standards and Science (KRISS), Daejeon 34113, Korea.
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea.
ACS Nano. 2021 Nov 23;15(11):18113-18124. doi: 10.1021/acsnano.1c06752. Epub 2021 Nov 4.
Charge doping to Mott insulators is critical to realize high-temperature superconductivity, quantum spin liquid state, and Majorana fermion, which would contribute to quantum computation. Mott insulators also have a great potential for optoelectronic applications; however, they showed insufficient photoresponse in previous reports. To enhance the photoresponse of Mott insulators, charge doping is a promising strategy since it leads to effective modification of electronic structure near the Fermi level. Intercalation, which is the ion insertion into the van der Waals gap of layered materials, is an effective charge-doping method without defect generation. Herein, we showed significant enhancement of optoelectronic properties of a layered Mott insulator, α-RuCl, through electron doping by organic cation intercalation. The electron-doping results in substantial electronic structure change, leading to the bandgap shrinkage from 1.2 eV to 0.7 eV. Due to localized excessive electrons in RuCl, distinct density of states is generated in the valence band, leading to the optical absorption change rather than metallic transition even in substantial doping concentration. The stable near-infrared photodetector using electronic modulated RuCl showed 50 times higher photoresponsivity and 3 times faster response time compared to those of pristine RuCl, which contributes to overcoming the disadvantage of a Mott insulator as a promising optoelectronic device and expanding the material libraries.
对莫特绝缘体进行电荷掺杂对于实现高温超导、量子自旋液体态和马约拉纳费米子至关重要，这将有助于量子计算。莫特绝缘体在光电子应用方面也具有巨大潜力；然而，在先前的报道中它们表现出光响应不足。为了增强莫特绝缘体的光响应，电荷掺杂是一种很有前景的策略，因为它能有效改变费米能级附近的电子结构。插层是将离子插入层状材料的范德华间隙中，是一种有效的电荷掺杂方法且不会产生缺陷。在此，我们通过有机阳离子插层进行电子掺杂，展示了层状莫特绝缘体α-RuCl光电子性质的显著增强。电子掺杂导致电子结构发生实质性变化，使带隙从1.2 eV缩小到0.7 eV。由于RuCl中存在局域化的过量电子，在价带中产生了明显的态密度，即使在大量掺杂浓度下也导致光吸收变化而非金属转变。使用电子调制RuCl的稳定近红外光电探测器与原始RuCl相比，光响应度提高了50倍，响应时间快了3倍，这有助于克服莫特绝缘体作为一种有前景的光电器件的缺点，并扩展材料库。
