Significantly Increased Photoresponsivity of WSe2‐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 (WSe2) 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 WSe2, which suggests the charge transfer from Au‐TPP to WSe2. For optoelectronic applications, photoresponsive field‐effect transistors (FETs) based on pristine WSe2 and WSe2/Au‐TPP hybrids are fabricated and compared. After the hybridization with Au‐TPP, the charge transport characteristics of the WSe2‐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 WSe2/Au‐TPP‐based FETs owing to their efficient light absorption and charge transfer from Au‐TPP to WSe2. Field‐effect transistors using WSe2/gold(III)‐tetraphenylporphyrin (Au‐TPP) hybrids demonstrate a change in electrical behavior from weak ambipolar to strong n‐type and a tremendous increase in photoresponsivity, which depends on the concentration of Au‐TPP. The photoluminescence quenching and the decrease of exciton lifetime of Au‐TPP after hybridization with WSe2 indicate charge transfer from Au‐TPP to WSe2. [ABSTRACT FROM AUTHOR]