The Numerical Simulation Of Micro-nano-structured Photovoltaic Cell

The appropriate application of nanostructure materials can increaselight absorption, enhance the efficiency of electron transfer, improve thetransmission of the carrier, thus to build up the energy conversionefficiency of the solar cell. In this paper, the excellent characteristics ofnanostructure material were used for designing the amorphous silicon/nanostructure silicon-germanium alloy/crystalline silicon（a-Si:H/nc-SiGe/c-Si） heterojunction solar cells, P3HT:PCBMheterojunction organic solar cell as well as In_xGa_1-xN/InN quantum dotintermediate band solar cell. The Photovoltaic properties of the three kindcells were also studied by numerical simulation. The studies are asfollows:1. Firstly, the structure of the amorphous silicon/nanostructuresilicon germanium alloy/crystalline silicon （a-Si:H/nc-SiGe/c-Si）heterojunction HIT solar cell was designed. And the influences ofgermanium content, grain size, crystalline volume fraction and temperature on the electrical properties of the solar cell were studied aswell. The results indicated that the optimum germanium content insilicon-germanium alloy material is about10%, and the temperaturedependence of the10%germanium content solar cell is weaker. With theincrease of the mean grain size and crystalline volume fraction, the opencircuit voltage of the cell reducing slightly, while the short circuit current,fill factor, and conversion efficiency are all increasing.2. Secondly, the P3HT: PCBM organic heterojunction solar cell wasdesigned. Optical transmission matrix model and effective medium modelwere used as the optical and electrical models, respectively, and theoptical and electrical properties of the solar cell were solved by usingfinite element method. By adding the ZnO anode and GO cathodemodified layer and changing the refractive index （n） and the dispersioncoefficient （k） of the modified layer material, we studied the influence ofthe light absorption efficiency of the modification layer on the activelayer. The impact of different carrier injection barrier on solar cellperformance was also studied in this section. The results suggested thatwith the increase of the refractive index and the dispersion coefficient ofthe modified electrode layer, the light field intensity of absorption layerreduced. When the carrier injection barrier is zero, the efficiency of thecell is optimal.3. Finally, we simulated In_xGa_1-xN/InN quantum dot intermediate band solar cell and calculated the impact on solar cell performance ofindium content, quantum dot size, the inter-dot distance. The resultsshowed that in In_xGa_1-xN barrier materials, the optimum content ofindium keeps a value under the condition of determined quantum dot sizeand varied inter-dot distance; but if we change the quantum dot size, theoptimum content changes. Another finding was that the short-circuitcurrent of the cell is substantially independent from the inter-dot distance,but influenced by the size of the quantum dots. For In_xGa_1-xN/InNquantum dot intermediate band solar cell, the performance of solar cellwith one intermediate band is better than the one with two intermediatebands.