Metal Nanoclusters Modify the Band Gap and Maintain the Ultrathin Nature of Semiconducting Two-Dimensional Materials

Modifying the band gap of semiconducting two-dimensional materials (S2DM), such as monolayer molybdenum disulfide (MoS2) is useful in ultrathin optoelectronic applications. Electron doping is an efficient technique to alter the electronic band gap and change exciton binding energy of MoS2, thus modifying the optical band gap. Photoexcited silver nanoclusters (AgNCs) can produce a large number of energetic hot-electrons with a lifetime in the hundreds of picoseconds time scale. These hot-electrons can inject into the conduction band of a single layered MoS2 thereby modifying its optoelectrical properties when AgNCs come in contact with the sheet. Additionally, increasing AgNCs coverage density on MoS2 surface increases the electron doping density. At low AgNCs coverage density, the absorption and photoluminescence (PL) spectrum of MoS2 are red shifted as a result of band gap renormalization. The magnitude of the red shift increases as the coverage density of AgNCs is increased before blue-shifting remarkab...