PbS nanoparticles could become low-cost photodetectors
A simple technique for assembling lead sulfide (PbS) nanoparticles into micron-sized thin crystalline sheets could lead to exceptionally low-cost photodetectors.
A simple technique for assembling lead sulfide (PbS) nanoparticles into micron-sized thin crystalline sheets could lead to exceptionally low-cost photodetectors. Conventional nanoparticle assembly techniques that rely on organic shells require the nanoparticles to be treated after they are assembled to remove the insulating shells. But the approach developed by scientists at the University of Hamburg (Germany), which brings PbS particles together into stacked layers of 2D sheets about 2 nm thick, uses chlorine-containing compounds to drive colloidal assembly of the particles without the need for organic shells. The stacked sheets have a strong crystalline correlation.
The researchers bridged two gold electrodes with the 2D PbS sheets to test their photoconductivity. The dark conductance was low between -0.1 and 0.1 V; however, when illuminated with light from a 532 nm laser at an intensity of 2.0 mW/cm2, the conductance rose by more than two orders of magnitude, corresponding to a responsivity of 0.472 A/W at 0.1 V. The sheets, which were used as fabricated with no additional treatment, have a continuous electrical connection throughout the monocrystalline structures. Contact Horst Weller at email@example.com.