化學修飾石墨烯與矽之蕭基接面高效率光伏元件

Abstract

石墨烯為一獨立的二維材料，擁有許多特別的性質。得益於此單原子層結構的石墨烯非常敏感，容易被化學摻雜物修飾。除了可調控的功函數之外，其高穿透度及高導電性，在蕭基接面太陽能電池領域成為極具潛力可取代金屬電極的材料。 在此論文的第一部分，我們應用一雙面修飾的方法試圖調控石墨烯的兩個表面。以金奈米粒子修飾石墨烯底面可改善石墨烯與矽基板的接觸，兼之上表面以TFSA分子進行化學摻雜。最後經雙面修飾的石墨烯製成的石墨烯與矽蕭基接面太陽能電池達到了11.8%的高光電轉換效率。在第二部分，我們開發了一種奠基於簡單氧化還原反應及溶劑製程的方法，能夠以金粒子填補石墨烯裂縫及破洞。金填補過後的石墨烯用於蕭基接面太陽能電池，加上TFSA分子化學摻雜後，達到了目前此結構無抗反射技術的最高效率12.2%，且其高填充因子（78.8%）甚至近於傳統p-n接面太陽能電池的表現。

Graphene, a free-standing 2D material, has a lot of special properties. Benefitting by this single-atom-layer structure, the graphene film is very sensitive, possessing the potential to be modified with chemical dopants. Besides the tunable work function, its high transparency and conductivity make it a promising material to replace metal electrode in Schottky junction solar cell. In the first part of this thesis, a method of bifacial modification is applied to play with the two surface of graphene. With modifying the bottom side of graphene with gold nanoparticles, the contact between graphene and silicon can be improved. Then along with top doping by bis(trifluoromethanesulfonyl)amide (TFSA), the two surfaces of graphene can both be treated. The final bifacially modified device reaches a high power conversion efficiency (PCE) of 11.8%. In the second part, a solution method based on simple oxidation-reduction reaction is derived to fill the cracks of graphene with gold particles. The PCE of Au-filled graphene-Si Schottky junction photovoltaic with TFSA doping reaches the highest value (12.2%) of this junction without antireflection technique to date, and its high fill factor (78.8%) is even close to the performance of conventional silicon p-n junction solar cell.