Light management in hybrid organic/Gallium arsenide solar cell
|關鍵字:||混合型太陽電池;砷化鎵;hybrid solar cells;GaAs|
|摘要:||近幾年興起以有機材料搭配無機半導體之混合式太陽電池備受矚目。目前由P-type的PEDOT:PSS加上N-type砷化鎵混合型太陽電池效率可達7%。本論文主要研究分為三部分:其一，利用表面結構增加吸光機率，在濕蝕刻技術上利用硝酸配硫酸和氨水配雙氧水進行蝕刻，成功將反射率降至13%並使元件的光電流從17.49 mA/cm2提升23.31 mA/cm2，平均光電轉換效率從7.8%提升9.4%。在乾蝕刻技術上，反射率降至8.86%並使元件的平均光電流從16.17 mA/cm2提升19.60 mA/cm2，平均光電轉換效率從7.11%提升7.42%。
其二在有結構的砷化鎵元件旋上有機層TAPC / Green B，其有機層可視為中間複合層，降低表面複合的機會且提升Voc。元件最佳結果開路電壓0.645V、短路電流25.15 mA/cm2、填充因子61.78%、光電轉換效率達到10%。
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.