Ag nanoparticle-decorated single wall carbon nanotube films for photovoltaic applications

We report on the use of pulsed laser deposition to decorate single wall carbon nanotube (SWCNTs) films with Ag nanoparticles (NPs) in hybrid SWCNTs/n-Si photovoltaic (PV) devices. PV devices are built by coating n-Si surfaces with a controlled density of a SWCNTs’ suspension via an air-brush method. By adjusting the number of laser pulses (N Lp) from the KrF laser, we are able to control the size and density of the Ag NPs covering the SWCNTs films. Through adjustment of N Lp, we are able to improve the power conversion efficiency of the SWCNTs/n-Si devices from 3.5 to over 6 % at N Lp = 1250 and the corresponding fill factor (FF) from 35 to 60 %. This increase is shown to be correlated with Raman, electrical and optical properties of the Ag NPs-coated SWCNTs films. UV–Vis spectroscopy measurements show the presence of optical scattering that is directly attributed to the presence of plasmon in the range of 450–600 nm and internal quantum efficiency measurement shows significant improvement over this range. In addition to this direct increase of the generate photocurrent, the overall Ag NPs film resistance is sufficiently lowered to ensure higher FF and thus a higher PCE. Beyond the optimal value of N Lp > 1250, we show that the decreasing PCE is caused by low optical transmission of the Ag NPs films and poorer rectification.