Novel INFIQ® Lead-Free Infrared Quantum Dot Inks for Photovoltaic Applications

胶体量子点(CQD)具有从可见光到红外(IR)的带隙，在下一代光伏(PV)领域受到了极大的关注。CQD具有高效的多重激子产生(MEG)、能级可调、低成本和可扩展的溶液工艺(例如适用于各种基材(包括玻璃和柔性塑料)的开槽模涂覆和喷墨打印)。CQD具有高的吸收系数，因此几百纳米的CQD薄膜足以吸收传统的晶体硅太阳能电池(SCs)和其他新兴的PVs所无法获得的红外太阳光。在串联电池结构中将窄禁带红外量子点与现有的光伏系统(如晶体硅和钙钛矿)相结合，可以提高所得到的SC的能效和密度。QDSolar Inc.已经报道了基于钙钛矿和红外量子点的工业串联太阳能电池的效率超过20%。到目前为止，铅基纳米材料的记录效率已经被报道，这种材料是RoHS指令2011/65/EU中限制的危险物质，引起了环境和健康问题。此外，CQD SCS中的CQD有源层通常是通过固体配体交换结合多层逐层沉积工艺来制备的，每一层都需要进行化学处理和清洗，以去除绝缘的大块有机配体，以实现高纳米晶体的堆积密度和电荷传输。昂贵的工艺一直是高通量加工的主要障碍。此外，多层沉积产生了很高的缺陷概率，并对实现大基片高度均匀的薄膜提出了挑战。到目前为止，基于溶液的CQD-SC制备主要是使用小衬底在实验室规模进行演示。总部位于英国的创新者量子科学有限公司(QS)开发了一种新型的无铅红外量子点(INFIQ(R)LF-Qds)，这种量子点对环境友好，可以有效地将太阳光谱中的可见光和红外光转化为电能。该项目旨在开发新颖且可扩展的INFIQ(R)LF-QD油墨，克服目前CQD-SC大规模生产的挑战。实验室规模的光伏设备将使用开发的墨水来制造，以展示其性能以及材料和工艺的成本效益。生产的电池将在1太阳AM1.5的太阳辐射下进行测试，使用QS器件实验室的太阳模拟器，冠军电池将进行外部验证。参考文献：1.Kirmani_et al.，_acs Energy Letters，2020年，5，9,30692。Https://www.nrel.gov/pv/cell-efficiency.html3.Https://qdsolarinc.com/

Colloidal quantum dots (CQDs) with bandgap from visible to infrared (IR) range have received great attention for next-generation photovoltaics (PVs). The CQDs offer the advantages of efficient multiple exciton generation (MEG), tunable energy level, low cost and scalable solution process (such as slot die coating and inkjet printing for diverse substrates including glass and flexible plastics). The CQDs have high absorption coefficients, so the CQD thin films of a few hundred nanometres are sufficient to absorb infrared sunlight, which is barely harvested by conventional crystalline silicon solar cells (SCs) and other emerging PVs \[1,2\]. Incorporation of narrow bandgap IR CQDs with existing PV systems such as crystalline silicon and perovskites in a tandem cell structure can boost energy efficiency and density of the resultant SCs. Industry tandem solar cells based on the perovskites and IR quantum dots with efficiency over 20% have been reported by QDSolar Inc. \[3\].To date, the record efficiency has been reported for lead-based nanomaterials which are restricted hazardous substances under RoHS Directive 2011/65/EU causing environmental and health concerns. In addition, the CQD active layers in the CQD SCs are commonly fabricated by using solid ligand exchange combined with multiple layer-by-layer deposition process, where each layer requires chemical treatment and washing to remove insulating bulky organic ligands to enable high nanocrystals packing density and charge transport. The costly process has been a major obstacle for the high-throughput processing. Moreover, the multilayer depositions create high probability of defects and challenges to achieve high uniform films for large substrates. Until now the solution-based CQD-SC fabrications have been mainly demonstrated in laboratory scales using small substrates.UK-based innovator, Quantum Science Ltd (QS), has developed a new class of lead-free IR quantum dots (INFIQ(r) LF-QDs) that are eco-friendly and efficiently convert visible and infrared lights of the solar spectrum into electricity. This project aims to develop novel and scalable INFIQ(r) LF-QD inks, overcoming current CQD-SC mass production challenges. Lab-scale photovoltaic devices will be fabricated using the developed inks to demonstrate their performance, and cost effectiveness of the materials and process. The produced cells will be tested under 1 sun AM1.5 solar radiation, using solar simulator in QS device lab, and the champion cell will be validated externally.References:1. Kirmani _et al.,_ ACS Energy Letters, 2020, 5, 9, 30692. https://www.nrel.gov/pv/cell-efficiency.html3. https://qdsolarinc.com/