石墨烯透明电极光电性能调控机理研究

Graphene is a new type of transparent electrode materials with high optical transmittance, good electrical conductivity and low cost, and has potential applications in the optoelectronic and photovoltaic devices. In this project, the mechanism of photoelectric property control for graphene transparent electrode is investigated in polymer solar cells. The influences of graphene’s parameters on spectral transmittance and conductivity and photovoltaic properties of solar cell are studied. Wide-angle x-ray scattering (WAXS) is performed in order to monitor the changes in structure of graphene oxide to produce highly repaird graphene, and the controllable growth of graphene film is realized. The mechanism of functional groups affecting spectral properties of graphene film is clarified. The law of optical field resonance in micro-cavity of the device is explored to consider the effect on optical field in micro-cavity of the device, and the optimal structure theory of graphene electrode is built. Based on these, the mechanism of photoelectric property control for graphene transparent electrode is illustrated, and the improved process of graphene electrode is obtained.

石墨烯是一类具有高的光学透过率和良好导电性且成本低廉的新型透明电极材料，在光电显示及光伏器件领域具有潜在的应用价值。本项目以新型石墨烯透明电极材料在聚合物太阳能电池中的应用为背景，拟开展石墨烯透明电极光电性能调控机理的研究：考察一系列石墨烯薄膜参数对电极的光谱透过率、电导率以及太阳能电池光电性能的影响，研究石墨烯可控性生长规律，通过采用同步辐射小角X射线散射对氧化石墨烯表面结构变化的原位监控实现薄膜结构的“纳米修补”，澄清功能化石墨烯官能团影响石墨烯薄膜光谱特性的微观机理，探索石墨烯-电池功能层－金属微腔结构的光电场谐振规律，揭示光学微腔效应对电池光电场的影响规律，建立石墨烯电极结构的优化理论，进一步阐明石墨烯电极性能光电调控的物理机理，通过改进工艺方法获得光电性能可替代ITO的石墨烯透明电极。

石墨烯及石墨烯氧化物薄膜层数与尺寸的可控性生长、薄膜缺陷与表面形貌控制，是石墨烯及石墨烯氧化物薄膜在薄膜光电器件中得以广泛应用所面临的基本问题。为此，选择浓度为0.25 mg/ml ~ 4mg /ml水性悬浮液来制备不同厚度的GO薄膜，采用UV-Vis和Raman光谱仪，研究了不同厚度GO衬底的透射光谱以及热退火对GO薄膜光电特性的影响；采用稳态PL光谱仪，研究了GO与光电功能层电荷转移行为。基于结构为ITO/GO/ CH3NH3PbI3 /PCBM/Ag的平面型器件，对GO薄膜及器件的光电性能进行了研究。并开展了GO作为串联型太阳能电池导电过渡层对器件内光电场调控能力的研究。结果表明：通过旋涂工艺制备的GO衬底，具有较高的电荷转移效率。与其它浓度的分散液制备的GO衬底相比，浓度为0.25mg/ml对应的GO衬底具有明显的孔洞缺陷，从而破坏CH3NH3PbI3晶粒的择优取向生长，形成可诱导CH3NH3PbI3晶粒产生横向聚集的籽晶，从而改善钙钛矿薄膜的成膜性，并增大钙钛矿晶粒尺寸。获得了光电转换最高可达8.69%的反型结构GO基钙钛矿太阳能电池。此外，石墨烯作为串联太阳能电池的过渡层，对光学微腔器件光电场分布的影响有限，而薄层金属银能够更好地避免有机太阳能电池中的光学死区效应，改善器件的光学吸收。