膠體量子點對於大面積砷化鎵太陽能電池之影響及應用

Abstract

本研究製作多種面積與幾何結構之砷化鎵（GaAs）太陽能電池，以探討元件尺寸、形狀與量子點材料對元件光電特性的影響。首先分別製作小面積與大面積太陽能電池，並設計四種幾何形狀，包括方形 (square)、回字形 (hollow)、十字形 (cross)與ㄇ字形 (u- shape)。研究中，分別使用膠體量子點（colloidal quantum dots, CQDs）以定量吸管滴覆綠色量子點（GQDs）於元件表面或元件檯面（mesa）旁，並製作量子點光阻（quantum dot photoresist, QDPR）薄膜。 透過 J–V 曲線和外部量子效率（External Quantum Efficiency, EQE）量測，觀察其對元件性能的影響。實驗結果顯示，直接滴覆 GQD 於元件表面效果最為顯著，其中回字形與ㄇ字形元件的短路電流分別增加約 5% 與 12%。外部量子效率分析不同濃度量子點及元件側壁的影響，結果同樣顯示表面滴覆效果最佳。製作紅色與綠色 QDPR 薄膜後，進一步計算藍光及 UV 光下的色彩轉換效率（color conversion efficiency, CCE），結果證實量子點材料可透過Luminescent Downshifting (LDS) 效應，將高能光子轉換為適合 GaAs 吸收的光子，有效提升光吸收與載子收集效率。同時評估將薄膜置於元件檯面旁的 J–V 變化。 綜合而言，本研究證明透過幾何設計與量子點材料整合，可有效提升 GaAs 太陽能電池光電性能，並為高效率太陽能電池提供新的思路。

This study fabricated GaAs solar cells with various device areas and geometrical structures to investigate the effects of device size, geometry, and quantum dot materials on their photovoltaic performance. Small- and large-area solar cells were prepared with four different geometries, including square, hollow, cross, and u-shape designs. Colloidal quantum dots (CQDs) were dispensed using a calibrated pipette to deposit green quantum dots (GQDs) either directly on the device surface or beside the device mesa. In addition, quantum dot photoresist (QDPR) films were prepared. The device performance was characterized by J–V measurements and external quantum efficiency (EQE). Experimental results show that direct GQD deposition on the device surface yields the most significant improvement, with the short-circuit current increased by approximately 5% and 12% for hollow and U-shaped devices, respectively. EQE analysis of different quantum dot concentrations and device sidewalls further confirms that surface deposition provides the optimal effect. Red and green QDPR films were also prepared, and the color conversion efficiency (CCE) under blue and UV illumination was calculated. The results demonstrate that the quantum dot materials can enhance light absorption and carrier collection the luminescent downshifting (LDS) effect, converting high-energy photons into photons suitable for GaAs absorption. The impact of placing the films beside the device mesa on J–V characteristics was also evaluated. Overall, this study demonstrates that integrating geometrical design with quantum dot materials can effectively enhance the photovoltaic performance of GaAs solar cells and provides valuable guidance for the design of high-efficiency solar cells.