Insulating 6,6-Phenyl-C61-butyric Acid Methyl Ester on Transition-Metal Dichalcogenides: Impact of the Hybrid Materials on the Optical and Electrical Properties.

In this study we develop a strategy to insulate 6,6 -Phenyl C 61 butyric acid methyl ester (PCBM) on the basal plane of transition metal dichalcogenides (TMDs). Concretely single layers of MoS 2 , MoSe 2 , MoTe 2 , WS 2 , WSe 2 and WTe 2 and ultrathin MoO 2 and WO 2 were grown via chemical vapor deposition (CVD). Then, the thiol group of a PCBM modified with cysteine reacts with the chalcogen vacancies on the basal plane of TMDs, yielding PCBM-MoS 2 , PCBM-MoSe 2 , PCBM-WS 2 , PCBM-WSe 2 , PCBM-WTe 2 , PCBM-MoO 2 and PCBM-WO 2 . Afterwards, all the hybrid materials were characterized using several techniques, including XPS, Raman spectroscopy, TEM, AFM, and cyclic voltammetry. Furthermore, PCBM causes a unique optical and electrical impact in every TMDs. For MoS 2 devices, the conductivity and photoluminescence (PL) emission achieve a remarkable enhancement of 1700 % and 200 % in PCBM-MoS 2 hybrids. Similarly, PCBM-MoTe 2 hybrids exhibit a 2-fold enhancement in PL emission at 1.1 eV. On the other hand, PCBM-MoSe 2 , PCBM-WSe 2 and PCBM-WS 2 hybrids exhibited a new interlayer exciton at 1.29-1.44, 1.7 and 1.37-154 eV along with an enhancement of the photo-response by 2400, 3200 and 600 %, respectively. Additionally, PCBM-WTe 2 and PCBM-WO 2 showed a modest photo-response, in sharp contrast with pristine WTe 2 or WO 2 which archive pure metallic character.