Photovoltaic Cells Based On Micro/nanostructured Silicon

This thesis investigates the photovoltaic cells based on micro/nanostructuredsilicon. The main investigation is focused on the synthesis of micro/nanostructruedsilicon, silicon surface passivation and device fabrication as well as characterization.And the main works include the following aspects:1The micro/nanostructured silicon is prepared via simple and efficient wetchemical etching method. The structure exhibites strong light harvesting capability. Inaddition, the device based on core/shell heterojunction structure can decouple the lightabsorption and charge transport, whereas the charge carries can diffuse only a shortdistance radially to the junction. Hence, it ought to be possible to relax the materialscost providing that using less and lower quantity silicon materials.2A monolayer of chemical group is anchored onto the silicon surface by wetchemical technology. It indicates that a good passivation could dramatically reduce thedensity of trap states on silicon surface, decreasing the surface charge-carrierrecombination velocities, as well as the diffusion of oxygen into silicon. Furthermore, itcan tune the surface potential via different organic molecules to optimize the deviceperformances.3Photoelectrochemical cells (PEC) has been built up based on silicon microholearrays (SiMHs), in which the ionic liquids (ILs), including I-/I3-redox pairs, is used aselectrolyte. The ILs displays stable and wide redox windows as well as high chargecarrier mobility, and resulting in high performance. The results show that the powerconversion efficiency can reach4.03%using the SiMHs as the photoactive layer, whichis dramatically improved in compared with the planar silicon PEC cells (0.53%).4An organic-inorganic hybrid heterojunction solar cell has been fabricated basedon silicon nanowire arrays (SiNWs), Poly(3-hexylthiophene)(P3HT) as the holetransport layer (HTL). In this type of solar cell, both the interface between organic andinorganic layer and the properties of HTL play important roles on the device performances. The optimized device performance can achieve a power conversionefficiency of6.56%via effective surface passivation and doping on HTL.