Polymer solar cells (PSCs) are one of the cost-effective alternatives to the traditional silicon-based solar cell. To be commercially viable, a number of its shortfalls have to be addressed. First, the charge mobility and life time of the organic materials used in PSCs are low and results in a large series resistance and inefficient charge separation. Second, the range of absorption of light in PSCs is not wide enough to cover the whole solar spectrum. Hence, the highest power conversion efficiency (PCE) achieved by PSCs is still low compare to other types of solar cells. In this thesis, several methods were investigated to improve the PCE of PSCs base on the donor polymer Poly(3-hexylthiophene-2,5-diyl) (P3HT) and acceptor fullerene Phenyl-C61-butyric acid methyl ester (PCBM). It was found to be essential to control the drying rate of the solvent after spin-coating the polymer solution on a piece of glass as it would affect the ordering and crystallinity of the polymer chains. Besides, instead of a bulk heterojuction (BHJ) structure, a bilayer device can also give a comparable PCE by spin-coating P3HT and PCBM separately using orthogonal solvents. Factors that could affect the performance of bilayer devices, such as the drying rate and thermal annealing, were investigated. It was found that thermal annealing is essential since it would facilitate the interdiffusion of the two layers. In order to improve the range of spectral absorption of light, a squaraine dye was introduced. Squaraine has a high absorbance in the near-infrared range where the absorption is poor for P3HT. The PCE was found to increase by about 5 % by incorporating 0.5 wt % of squaraine into the BHJ system. In addition, squaraine was introduced to the bilayer system. It was found that the performance was slightly improved when squaraine was blended with PCBM in the upper layer. Various parameters were tuned to optimize the performance of this bilayer system. / 聚合物太陽能電池是其中一個比傳統晶體矽太陽能電池有更高成本效益的代替品。然而，聚合物太陽能電池仍然有若干缺點需要解決才能夠成為商業市場上流通的產品。首先，聚合物太陽能電池所使用的有機材料的電荷遷移率和壽命低，造成較大的串聯電阻和低效率的電荷分離。其次，聚合物太陽能電池的吸收光譜範圍較窄，不足以覆蓋整個太陽光譜。因此，相比起其他類型的太陽能電池，聚合物太陽能電池的最高能量轉換效率仍然偏低。在本論文中，我們建基於供體P3HT和受體PCBM' 進行了多分面的研究。我們發現旋塗聚合物溶液後，控制溶劑的乾燥速度是很重要的，因為這會影響聚合物鏈的排序和結晶度。另外，除了體異質接面結構外，利用正交溶劑來分別旋塗P3HT和PCBM的雙層結構亦可得到可比的最高能量轉換效率。我們研究了數個可能影響雙層結構聚合物太陽能電池效能的因素，例如乾燥速度和熱退火處理，並發現熱退火處理是非常重要，因為熱退火可以有利於兩層聚合物的相互擴散。為了擴闊電池的吸收光譜範圍，我們引入了方酸染料。方酸在近紅外線範圍內具有高的吸光率，而在此範圍內P3HT的吸光率都欠佳。在慘雜0.5重量百分比的方酸到原有的體異質接面結構後，最高能量轉換效率提升了大約百分之五。此外，方酸也才參雜到雙層結構系統內，結果發現，當方酸慘雜在上層中的PCBM後，電池的效能稍有改善。我們調整了各種參數，以完善該雙層系統的效能。 / Chow, Chun Yin = 雙層及摻雜染料聚合物太陽能電池研究 / 周俊然. / Thesis M.Phil. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 90-92). / Abstracts also in Chinese. / Title from PDF title page (viewed on 07, October, 2016). / Chow, Chun Yin = Shuang ceng ji shan za ran liao ju he wu tai yang neng dian chi yan jiu / Zhou Junran. / Detailed summary in vernacular field only.