Low-cost Extremely Thinlayer Absorber (ETA) Solar Cell: A Novel approach to make the conformal ETA Layers

超薄吸收层(ETA)太阳能电池是一种相对较新的光伏配置。从材料的角度来看，有大量的半导体材料适合用于ETA单元配置。其中大部分还有待于在ETA细胞中进行测试。该项目的第一部分将旨在筛选半导体材料组合，以找到用于ETA电池的新材料组合(高带隙n型半导体/低带隙吸光半导体/高带隙p型半导体)。这将通过调整半导体的带隙和带边来实现。该项目的下一部分是建造ALD和CVD集成沉积系统。构建该沉积系统的主要优点是可以在高深宽比的微结构上沉积共形层的低禁带半导体吸光材料。该系统还将能够沉积无针孔的致密层和在高深宽比微结构上沉积p型高禁带半导体。首先，利用喷雾热解(用作阻挡层)在FTO衬底上沉积致密的高禁带金属氧化物半导体薄膜。为了进行比较，还将采用集成沉积系统来制作致密的阻挡层。然后在致密层上沉积相同带隙半导体的微结构多孔膜。为此，将从一系列方法(即，溶胶-凝胶胶体的丝网印刷、溶胶-凝胶胶体的医生刀片、模板辅助电沉积、喷雾热解)中选择一种合适的沉积方法。然后利用集成的ALD和CVD沉积系统沉积出一层共形的吸光半导体材料(即CuInS2，Bi2S3，Cu2S，In2S3)。通过合适的方法(如喷雾热解、浸渍镀膜、电沉积、ALD/CVD集成方法或这些方法的组合)在保形层上沉积高禁带p型半导体(即CuI、CuCNS、CuAlO2)。这将在沉积Au背面触点之后进行。完成后的电池将通过一系列技术(即光电流光谱、稳态电流-电压曲线、强度调制光电流光谱和电荷提取技术)来表征，以研究电池的限制因素。所产生的信息将被馈送到电池制造中，以提高光捕获效率、光电压和整体转换效率。该项目将由一名具有必要技能的博士后研究助理进行，为期三年。在整个项目中，他将得到一名敬业的博士生(由拉夫堡大学理学院全额资助)的支持。我们将与我们的工业合作伙伴(BAC2有限公司和PolySolar有限公司)定期举行会议。行业合作伙伴的浓厚兴趣和他们的定期投入是该项目的一个关键优势。在这项工作的基础上，将出现新的想法、合作和跨学科项目，并将申请进一步的资金。总体而言，该项目将为英国下一代太阳能电池研究带来新的能力。

The Extremely Thin Absorber-layer (ETA) solar cell is a relatively new PV configuration. In materials viewpoint, there are a large number of semiconductor materials available that are suitable to employ in ETA cell configuration. Most of them are yet to be tested in ETA cell. The first part of the project will be aimed at screening semiconductor material combinations to find out novel material combinations (high band gap n-type semiconductor/low band gap light absorbing semiconductor/high band gap p-type semiconductor) for ETA cells. This will be done by aligning the band gap and band edges of semiconductors. The next part of the project is the construction of the integrated ALD and CVD deposition system. The main advantage of constructing this deposition system is that it will give us the capability of depositing conformal layers of light absorbing low band gap semiconductor materials on high aspect ratio of microstructures. The system will also be capable of deposition of pin-hole free compact layers and deposition of p-type high band gap semiconductors on high aspect ratio microstructures. Initially, a compact high band gap metal oxide semiconductor thin film will be deposited on FTO substrates using spray pyrolysis (to be used as a blocking layer). For the comparison the integrated deposition system will also be employed to make compact blocking layers. Then a microstructured porous film of the same high band gap semiconductor will be deposited on the compact layer. For this, a suitable deposition method will be selected from a range of methods (i.e. screen printing of sol-gel colloid, doctor-blading of sol-gel colloid, template assisted electrodeposition, spray pyrolysis). Then a conformal layer of light absorbing semiconductor material (i.e. CuInS2, Bi2S3, Cu2S, In2S3) will be deposited by using the integrated ALD and CVD deposition system. A high band gap p-type semiconductor (i.e. CuI, CuCNS, CuAlO2) will be deposited on the conformal layer by a suitable method (i.e. spray pyrolysis, dip coating, electrodeposition, integrated ALD/CVD method, or a combination of these methods). This will follow the deposition of a Au back contact. The completed cells will be characterised by a range of techniques (i.e. photocurrent spectroscopy, steady-state current-voltage plots, intensity modulated photocurrent spectroscopy and charge extraction technique) to study the limiting factors of cells. The resulting information will be fed into cell fabrication in order to improve light harvesting efficiency, photovoltage, and overall conversion efficiency. The project will be carried out by a postdoctoral research assistant who has the necessary skills over a period of three years. He will be supported by a dedicated PhD student (fully-funded by the Faculty of Science, Loughborough University) throughout the project. Regular meetings will be held with our industrial partners (Bac2 Ltd and PolySolar Ltd). The keen interest of industrial partners and their regular input is a key advantage for the project. Based on this work, new ideas, collaborations, and interdisciplinary projects will emerge and further funding will be applied for. In overall, the project will bring new capabilities to UK next generation solar cell research.