| Summary: | 碩士 === 國立交通大學 === 光電工程研究所 === 102 === In recent years, the emergence of hybrid organic and inorganic semiconductor solar cells attracts a lot of attention. Currently, GaAs hybrid solar cells which combine p-type PEDOT:PSS with n-type Gallium Arsenide(GaAs) can achieve a power conversion efficiency (PCE) of 7%. This thesis is divided into three parts. In the first part, we employ surface structures to increase the light absorption. By using a wet etching technique, we mix nitric acid with sulfuric acid and ammonia water mixed with hydrogen peroxide to etch GaAs surface. The reflectance was reduced to 13%, leading to a short-circuit current increase (Jsc) from 17.49 mA/cm2 to 23.3 mA/cm2 and an average PCE from 7.8% to 9.4%.By using a dry etching technique, the reflectance was reduced to 8.86%, leading to a Jsc increase from 16.17 mA/cm2 to 19.6 mA/cm2, and an average PCE from 7.11% to 7.42%. In the first part, we introduce organic materials TAPC and Green B into the GaAs interface. The intermediate layer functions as a recombination layer, which can reduce the chance of surface recombination and enhance the open-circuit voltage (Voc). The best device shows that the PCE can achieve 10% with Voc, Jsc and fill-factor equal to 0.645V, 25.15 mA/cm2, and 61.78%, respectively.
Finally, GaAs has high absorption coefficients and a thickness of several micrometers is enough for light absorption. According to the detailed balance theory, we can further enhance the Voc by placing a good mirror on the back of a cell. In the third part, we use the wafer lift-off process to remove the substrate of GaAs hybrid solar cell and then metal bond to a silicon substrate with a gold back reflector. Our experiment result shows that the wafer-bonding cell has an average Voc of 0.7V with a net increase of 0.04V, which is qualitatively consistent with the simulation result.
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