The characteristics of well-aligned silicon nanowire (SiNW)/poly(3,4-ethylenedioxy-thiophene): poly(styrenesulfonate) (PEDOT) heterojunction solar cells with varying nanowire lengths are investigated. PEDOT adheres on the hydrophilic n-type silicon nanowire surface to form a core-sheath heterojunction structure through the solution process. Such a structure increases the area of heterojunctions and shortens the carrier diffusion distance, and therefore, it greatly increases carrier collection efficiency. The cells exhibit stable rectifying diode behavior. Compared to the cells without a nanowire structure, the series resistance of the SiNW/PEDOT cell decreases from 60.42 Ω cm 2 to 1.47 Ω cm 2 , and the power conversion efficiency improves from 0.08% to 5.09%. The SiNW/ PEDOT solar cell harvests photons from 400 nm to 1100 nm and a maximum incident phototocurrent conversion efficiency of ∼32% at 700 nm.

No abstract

A new and general approach to achieving efficient electrically driven light emission from a Si-based nano p-n junction array is introduced. A wafer-scale array of p-type silicon nanotips were formed by a single-step self-masked dry etching process, which is compatible with current semiconductor technologies. On top of the silicon nanotip array, a layer of n-type ZnO film was grown by pulsed laser deposition. Both the narrow line width of 10 nm in cathodoluminescence spectra and the appearance of multiphonon Raman spectra up to the fourth order indicate the excellent quality of the ZnO film. The turn-on voltage of our ZnO/Si nanotip array is found to be approximately 2.4 V, which is 2 times smaller than its thin film counterpart. Moreover, electroluminescence (EL) from our ZnO/Si nanotips array light-emitting diode (LED) has been demonstrated. Our results could open up new possibilities to integrate silicon-based optoelectronic devices, such as highly efficient LEDs, with standard Si ultralarge-scale integrated technology.