Monolayer Semiconductor Optoelectronics

Ali Javey, Matin Amani, Der-Hsien Lien and Daisuke Kiriya


While two dimensional (2D) semiconductors show great promise for optoelectronic applications, due to a myriad of highly attractive properties which cannot be readily achieved in traditional III-V systems, to date they have shown tremendously poor photoluminescence quantum yield (QY). High QY is a requirement for materials used in key optoelectronic devices such as LEDs, lasers, and solar cells, since it determines the efficiency of light emission. Traditional three dimensional materials like GaAs require lattice matched cladding layers to obtain high QY, on the other hand 2D materials which have naturally terminated surfaces should be able to exhibit near-unity QY provided that there are no defects in the crystal. To this end, we have recently demonstrated that through chemical treatments with an organic superacid the defect sites on the surface of MoS2, the prototypical 2D material, can be repaired/passivated. Solution based treatment of defects is especially effective in monolayer semiconductors since the entire "bulk" of the semiconductor is also the surface. As a result the QY can be enhanced from less than 1% to over 95%. In this project we seek to expand this treatment to other 2D material systems as well as realize active devices based on perfect optoelectronic monolayers.