石墨烯具有許多適合光伏元件應用的特性，如：高光穿透性、機械可撓性、低阻抗及高載子遷移率。理論上，石墨烯因為有半金屬的特性，可以做為主動層與任何具有中等載子密度的半導體產生蕭基接面形成太陽能電池元件。
單層TMDs材料則是另一種具極高光電發展潛力的二維材料。與石墨烯不同，它們本身為半導體，且具有直接能隙，有高光電轉換效率的潛力。將單層TMDs材料與塊材基板結合製作光伏元件，可以有效彌補單層材料吸光區域有限的缺點，大幅提升其吸光能力並減少二維材料用量，增加量產可能性。
本研究分成兩個部份：轉移以化學氣相沉積法成長的單層MoS¬2、WS2與p型矽基板結合，形成異質接面太陽能電池；以及轉移同樣為化學氣相沉積法成長的石墨烯與n型砷化鎵結合，形成蕭基接面太陽能電池。
在矽基/TMDs材料元件部分，我們研究適合的背電極材料與上電極結構，找出具有最佳表現的組合。此研究中，MoS2及WS2與矽晶結合之太陽能電池光電轉換效率最高分別達4.23及2.08 %。
砷化鎵與石墨烯結合元件部分，我們分別比較純砷化鎵基板與以分子束磊晶技術在砷化鎵基板上磊晶成長砷化鎵薄膜並調變薄膜之摻雜濃度製成之元件。此研究中，石墨烯與砷化鎵結合之太陽能電池光電轉換效率最高達2.08 %。

Graphene has shown superior properties suitable for photovoltaic devices, including high optical transmittance, high mechanical flexibility, low resistivity, and high carrier mobility. In theory, with the property of semi-metal, graphene is able to form Schottky junction with any semiconductor having moderate carrier density.
Monolayer Transition Metal Dichalcogenides (TMDs) are also promising two-dimensional materials in optoelectronic devices. Monolayer TMDs are semiconductors with direct band gap which is beneficial to optoelectronic usage. Combination of monolayer TMDs and bulk materials potentially can overcome the limited absorption problem of 2D materials and difficulties in mass production.
This work consists of two studies: Transferring the chemical vapor deposition (CVD) grown TMDs onto p-type Si substrates to produce heterojunction p-n solar cells, and transferring graphene which is also grown by CVD onto n-type GaAs to produce Schottky junction solar cells.
In TMDs heterojunction p-n solar cells, various back electrode materials and top electrode structures were tested. The best power conversion efficiencies obtained for the MoS2 and WS2 heterojunction solar cells are 4.23 and 2.08 %, respectively.
In grapheme/GaAs Schottky junction solar cells, we used either the GaAs substrate or GaAs thin films with various doping concentrations grown by molecular beam epitaxy. The best power conversion efficiency of grapheme/GaAs Schottky junction solar cells is 2.08 %.

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