Ultrasensitive water-processed monolayer photodetectors

Solution-processed photodetectors with high sensitivity over a broad spectral range are highly desirable for low-cost, large-area sensing applications in both industrial and scientific communities. In general, the detector sensitivities are limited by inefficient carrier dissociation and transport of materials and high contact Schottky barriers. Here we detail a combined method to make ultrasensitive water-processed photodetectors based on high-performance Langmuir–Blodgett (LB) monolayer transistors of semiconducting copper phthalocyanine (CuPc), using quasi one-dimensional (1D) ballistically-conductive single-walled carbon nanotubes (SWNTs) as point contacts. Operating at low biases, the monolayer photodetectors exhibit responsivities greater than 108 A W−1, detectivities greater than 7 × 1015 Jones, and high reproducibility. These results form the basis for new types of high-performance photodetectors for a variety of possible sensor applications.