Significantly Increased Photoresponsivity of WSe ₂ -Based Transistors through Hybridization with Gold-Tetraphenylporphyrin as Efficient n-Type Dopant

The control of electrical and optical characteristics of 2D transition-metal dichalcogenides (TMDCs) through charge doping is essential to optimize the performances of optoelectronic devices based on TMDCs. In this study, a few-layer tungsten diselenide (WSe ₂ ) is hybridized with organic gold(III)-tetraphenylporphyrin (Au-TPP) using a simple drop-casting method. Nanoscale optical characteristics, measured by laser confocal microscopy, reveal that the photoluminescence intensity and exciton lifetime of Au-TPP decrease after the hybridization with WSe ₂ , which suggests the charge transfer from Au-TPP to WSe ₂ . For optoelectronic applications, photoresponsive field-effect transistors (FETs) based on pristine WSe ₂ and WSe ₂ /Au-TPP hybrids are fabricated and compared. After the hybridization with Au-TPP, the charge transport characteristics of the WSe ₂ -based FETs change to severe n-type characteristics including a negative shift of the threshold voltage and increase in electron mobility. Significantly enhanced photoresponsivities (up to 310 times) are observed for the WSe ₂ /Au-TPP-based FETs owing to their efficient light absorption and charge transfer from Au-TPP to WSe ₂ .