CZTSSe Solar Cells from Nanoparticle Inks

未来的能源需求可以通过使用可再生和取之不尽的太阳能来解决，提供清洁、无限、经济和绿色的能源。全球光伏装机容量目前为140千兆瓦，预计在未来十年内将达到1TW的水平。采用光伏技术的太阳能发电目前主要是硅基光伏发电，需要昂贵的设备和工艺，大规模降低成本的计划有限。薄膜技术，如CdTe和铜(In，Ga)Se2(CIGS)，提供了一种成本较低的替代方案，这主要是由于使用了在线和低温工艺。虽然已经做出了相当大的努力来提高效率和降低成本，但薄膜光伏目前依赖于稀缺的、因此昂贵的资源和/或有毒元素。因此，替代薄膜材料将提供降低光伏每瓦成本的途径，同时仍显示出较低的输入能量要求。基于铜锌锡(S，硒)4(CZTSSe)吸收层的太阳能电池提供了这样的替代方案。尽管其历史较短，CZTSSe的记录效率仍为12.6%，主要限制是(I)低于预期的开路电压，并伴随着低能量光子的转换和收集载流子的低效率；(Ii)在整个制造过程中难以控制凯斯特石的晶体结构；以及(Iii)在制造过程中使用剧毒化学品肼来实现记录效率。本项目将以热注射法制备的CZTS纳米晶分散体(油墨)为原料。这项技术可以可靠地控制晶体结构、成分和掺杂，不会对环境造成任何风险。油墨很容易旋涂或喷涂在基材上，富硒气氛下的热处理促进了颗粒的生长，而不会损失晶体结构。为了使用该技术制造记录效率，需要设计吸收层和背接触层的微结构，以提供大颗粒，延长吸收层的整个厚度，并结合小的界面层，以确保良好的欧姆接触。这将通过在纳米晶体制备中去除长碳氢链状配体以及修改硒化程序来实现。此外，还将量化影响器件性能的衬底和工艺杂质的作用。我将生产纳米墨水、太阳能吸收器和光伏设备，并展示世界领先的成果。

Future energy demand can be addressed by using renewable and inexhaustible solar energy, providing clean, unlimited, economical and green energy. The world global photovoltaic (PV) capacity currently stands at >140 GW and is expected to reach levels of 1 TW within the next decade. Electricity generation from the sun employing PV technology is currently dominated by Si-based PV and requires expensive equipment and process and schemes for cost reduction on a large scale are limited. Thin film technologies such as CdTe and Cu(In,Ga)Se2 (CIGS), provide a lower cost alternative primarily due to the use of in-line and low-temperature processes. While considerable efforts have been made to increase efficiency and reduce costs, thin film PV currently relies on scarce and therefore expensive resources and/or toxic elements. Alternative thin film materials would therefore provide routes to reduce PV cost-per-watt while still exhibiting lower input energy requirements. Solar cells based on Cu2ZnSn(S,Se)4 (CZTSSe) absorber layers offer such an alternative.Despite its young history CZTSSe record efficiency stands at 12.6% and the major limitations are (i) a lower than expected open circuit voltage accompanied by a low efficiency at converting and collecting carriers from low energy photons; (ii) the difficulty in controlling the kesterite crystal structure throughout the fabrication process; and (iii) the use of hydrazine, a highly toxic chemical, in the fabrication process to achieve the record efficiencies. This project will use nanocrystal dispersions (inks) of CZTS fabricating from hot injection as the starting material. This technique can reliably control crystal structure, composition and doping and does not present any environmental risks. Inks are easily spin coated or sprayed on substrates and a heat treatment under selenium rich atmosphere promotes grain growth without loss of the crystal structure. In order to fabricate record efficiencies using this technique the microstructure of the absorber and back contact layers need to be engineered to provide large grains extending the full thickness of the absorber combined with a small interfacial layer to ensure a good ohmic contact. This will be achieved by the removal of long hydrocarbon chained ligand in the nanocrystal fabrication alongside modifications of the selenization procedures. In addition the role of substrates and process impurities affecting devices performances will be quantified. I will produce nanoparticle inks, solar absorber and PV devices and demonstrate world leading results.