【作者】 朱光；

【导师】 孙卓；

【作者基本信息】 华东师范大学 ， 纳米物理学， 2012， 博士

【摘要】 敏化太阳能电池作为一种新型的光伏电池,因其具有高效率,成本低廉且制作工艺简单的优点,从而日益受到人们的关注,成为目前研究的热点。从敏化太阳能电池的工作机理来看,敏化剂(染料及量子点)与半导体薄膜的界面接触、光阳极的结构、对电极的催化还原性能等是影响其光电转换效率的主要原因。本论文主要围绕敏化太阳能电池的光阳极和对电极制备进行研究,改善光阳极内部的界而接触、降低器件制作的成本,主要研究内容如下：一、共沉淀方法制备光致发光材料Y3Al5O12:Ce颗粒,并作为散光层材料应用于染料敏化太阳能电池。通过在纳米晶TiO2(P25)透过层表面增加Y3Al5O12:Ce散光层,可以增加波长400-450nm范围内的光吸收,提高电极的光散射和反射本领；同时Y3Al5012:Ce荧光粉颗粒作为下转换材料可以吸收短波段的光,发射长波段的光,增加光阳极对光的捕获能力。在一个标准太阳光(100mWcm-2, AM1.5G)下,使用P25/Y3Al5O12:Ce电极的染料敏化太阳能电池的转换效率达到7.91%,比纯的P25电极(6.97%)的提高了13.5%。二、微波法合成石墨烯和石墨烯/金纳米颗粒复合物,并利用电泳法将它们沉积石墨片基底上形成薄膜作为对电极应用于染料敏化太阳能电池。(1)电泳沉积制备石墨烯/碳纳米管复合薄膜作为对电极应用于染料敏化太阳能电池,并比较不同碳纳米管掺杂量对电池性能的影响。通过碳纳米管的掺杂,碳管在复合电极中像桥梁一样连接在石墨烯之间,填充了石墨烯之间的空隙,形成了一种独特的网状结构,提高了复合电极的导电性,从而提高电池的转换效率。当碳纳米管在复合物中含量是60%时,在一个太阳光照射(AM1.5G,100mWcm-2)下,电池达到最高的转换效率(6.17%),比纯石墨烯(3.63%)和纯碳管(5.48%)的分别提高了70%和13%。(2)电泳沉积制备石墨烯/金纳米颗粒复合薄膜作为对电极应用于CdS量子点敏化太阳能电池。与纯的石墨烯电极相比,高催化性的金纳米颗粒和高比表面积的石墨烯复合形成多孔的网状结构,提高了电极的电化学催化性和导电性。在一个太阳光照射(AM1.5G,100mW cm-2)下,基于石墨烯/金纳米颗粒复合对电极的CdS量子点敏化电池的转换效率为1.36%,比纯石墨烯(0.98%)的提高了39%。同时这个转换效率,也高于传统的Pt和Au对电极的转换效率(1.21%和1.32%)。三、微波辅助化学浴沉积制备TiO2/CdS, TiO2/CdSe和TiO2/CdS/CdSe电极并应用于量子点敏化太阳能电池。与传统的量子点敏化太阳能电池的光阳极制备方法相比较,通过微波的辐射作用,可以在量子点与TiO2之间产生一个好的连接,从而形成优越的界面接触,有利于电子传输,抑制电子复合,从而得到高的转换效率。分别使用微波辅助化学浴沉积法一步制备了TiO2/CdS、TiO2/CdSe和TiO2/CdS/CdSe电极应用于量子点敏化太阳能电池,在一个太阳光照射(AM1.5G,100mW cm-2)下,得到1.18%、1.75%和3.06%的转换效率。与单个的TiO2/CdS和TiO2/CdSe电极相比,TiO2/CdS/CdSe可以形成一种阶梯式能带结构和好的界面接触,利于电子的传输和收集,抑制复合电流,因此有效提高了光电转换效率。四、超声雾化热解法制备ZnO界面层和ZnO/CdS电极,应用于量子点敏化太阳能电池。(1)使用超声雾化热解法在TiO2薄膜上制备ZnO的界面层,改善TiO2/CdS之间的界面接触,同时增加了量子点的吸附,提高了电极的光散射和反射。在一个标准太阳光(100mWcm-2, AM1.5G)下,使用TiO2/ZnO/CdS电极的量子点敏化太阳能电池得到1.56%的转换效率,比纯的TiO2/CdS电极(0.99%)的提高了57%。(2)使用超声雾化热解法制备ZnO薄膜和CdS敏化剂应用于量子点敏化太阳能电池。使用超声雾化热解法制备的ZnO/CdS电极,在FTO/ZnO/CdS之间可以产生个好的接触界面,有利于电子的传输,抑制电子的复合,从而得到高的转换效率。在一个太阳光照射(AM1.5G,100mWcm-2)下,得到转换效率达到1.54%。更多还原

【Abstract】 Sensitized solar cells (SSCs) as a kind of novel photovoltaic device have attracted considerable attention due to their low production cost, simple technique and high power conversion efficiency. Based on the working mechanism of SSCs, the interface contact between the sensitizer (dye or quantum dots) and semiconductor film, the structure of photoanode, and the electrochemical catalytic activity of counter electrode are important factors for the device performance. In the thesis, we designed and fabricated the photoanode and counter electrodes by different techniques to improve the interface contact inside the photoande and reduce the cost, and the major contents of the thesis is summarized as follows:(1) Y3Al5O12:Ce photoluminescent materials were fabricated by the co-precipitation method and used as an effectiv a marked improvement in conversion efficiency (7.91%) compared with the cell without a scattering layer (6.97%).(2) Graphene and grapnene/Au nanoparticles composite were fabr e scattering layer on the top of the transparent layer of nanocrystalline Tio2for dye sensitized solar cells (DSSCs). Due to enhanced light harvesting via the improved absorption of Y3Al5O12:Ce layer in the range of400-450nm, increased light scattering and reflection, and the light down-converting performance of Y3Al5O12:Ce particles, under one sun illumination (AM1.5G,100mW cm-2), the as-prepared DSSCs with Y3Al5O12:Ce scattering layer shows icated by microwave method, and then as-prepared samples were deposited onto graphite substrate by electrophoretic deposition (EPD) and used as counter electrodes for SSCs.1. Graphene-carbon nanotubes (CNTs) composite films with different amounts of CNTs were fabricated by EPD and used as counter electrodes of DSSCs. When CNTs are incorporated into the composite, the electrical conductivity of composite film is enhanced due to the good network structure for conductive bridge of the gaps between graphene nanosheets, leading to an improvement in performance of DSSCs. A maximum conversion efficiency of6.17%under one sun illumination (AM1.5G,100m Wcm-2) has been achieved for the cell based on graphene-CNTs counter electrode with60%CNTs, which has an improvement of70%and13%compared with the cells with pure graphene (3.63%) and CNTs (5.48%) counter electrodes, respectively.2. Graphene-Au nanoparticle composite film was fabricated by electrophoretic deposition and used as a counter electrode for CdS quantum dot-sensitized solar cells (QDSSCs). Under one sun illumination (AM1.5G,100mW cm-2), the cell with grapnene-Au counter electrode shows a energy conversion efficiency of1.36%, which is an increase of39%compared to the cell with pure graphene counter electrode (0.98%), due to a superior combination between highly catalytic Au nanoparticle and conductive graphene network structure. In the meantime, the value is also higher than those of the cells employing conventional Pt (1.21%) or Au (1.32%) counter electrodes.(3) CdS, CdSe, and CdS/CdSe quantum dots (QDs) sensitized TiO2films were fabricated by using microwave assisted chemical bath deposition (MACBD) technique and used as photoanodes for QDSSCs. Compared with conventional fabrication methods, this technique can synthesize QDs rapidly and suppress their surface defects as well as form a good contact between QDs and TiO2film, which can improve the performance of the cell. TiO2/CdS, TiO2/CdSe and TiO2/CdS/CdSe were one-step fabricated by MACBD technique and used as a photoanode for QDSSCs, respectively. Under one sun illumination (AM1.5G,100mWcm"2), conversion efficiencies of1.18%,1.75%,3.06%have been achieved for QDSSCs based on these electrode, which is comparable to those by using conventional fabrication methods. Compared with single (CdS and CdSe) QDs, their co-sensitized structure can provide a superior ability owing to the extension of light absorption range and effective charge injection from QDs to TiO2and thus exhibits a higher conversion efficiency.(4) The ZnO interface layer and ZnO/CdS electrode were fabricated by using ultrasonic spray pyrolysis (USP) deposition and applied in QDSSCs. 1. The ZnO interface layer was deposited on screen-printed TiO2layer by using USP technique. The formation of an inherent energy barrier between TiO2and CdS films and the passivation of surface traps on the TiO2film caused by the introduction of ZnO layer, which can improve the interface contact between TiO2and CdS, increase the adsorbed amount of CdS QDs and light scattering. Under one sun illumination (AM1.5G,100mWcm-2), a conversion efficiency of1.56%has been achieved for QDSSCs with ZnO interface layer, which has an increase of57%compared to the cell without a ZnO interface layer (0.99%).2. Sensitized-type solar cells based on ZnO photoanode and CdS QDs as sensitizers, in which both ZnO films and CdS QDs are prepared using USP technique. A good contact at the interfaces of FTO/ZnO/CdS has been formed by USP, which favors electron transportation and suppresses its recombination. Under one sun illumination (AM1.5G,100mWcm-2), a conversion efficiency of1.54%has been achieved for QDSSCs based on USP deposited ZnO/CdS electrode.更多还原