Solution Processing of Bulk Semiconductors with a Thiol-Amine Solvent Mixture

使用硫醇胺溶剂混合物对块状半导体进行溶液加工

• 批准号: 1506189
• 负责人: Richard Brutchey
• 金额: $ 39万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506189&HistoricalAwards=false
• 关键词: Solution; Processing; Bulk; Semiconductors; Thiol

NON-TECHNICAL SUMMARY: Making low-cost semiconductor thin films on a large scale holds promise for improving a number of high-tech applications, including solar cells. High vacuum techniques can achieve excellent quality semiconductor thin films, but low deposition speeds, high cost, difficult scalability, and/or high processing temperatures can be limiting depending on the particular process and material to be deposited. A conceptually attractive alternate route involves pre-formation of a precursor solution (or semiconductor ink) followed by simple and inexpensive solution deposition of the ink onto a substrate by spray coating, roll-to-roll or screen printing, or dip coating. This provides a powerful driving force for the development of semiconductor inks; however, most bulk inorganic semiconductors are totally insoluble in common solvents, making ink formation by simple dissolution very difficult. This highlights the need for new "universal solvents," or alkahests, of inorganic semiconductors. With support from the Solid State and Materials Chemistry program in the Division of Materials Research, the principal investigator is utilizing a novel solvent mixture discovered by his research group to readily dissolve a broad scope of bulk inorganic materials to make solution processible semiconductor inks. Upon solution deposition of the resulting semiconductor inks, the research team is demonstrating that high-quality semiconductor thin films can be achieved using mild conditions. Integrated into this research plan is an outreach program specifically aimed at local community college students. The community college student demographic is among the least targeted in traditional chemistry outreach programs; however, the greater Los Angeles area is home to the largest number of community college students in the U.S. The principal investigator has partnered with Cerritos Community College, an institution with a large number of underrepresented students, to provide internships on materials research. The objective of this annual 8-week outreach program is to provide these students with STEM research opportunities that are not afforded to them at the community college level, and thereby increase their transfer rate to 4-year institutions.TECHNICAL SUMMARY: Despite over fifty years of developments in the field of solid-state and materials chemistry, there are still only a limited number of ways to deposit inorganic semiconductor thin films - the majority of which require harsh and energy intensive conditions. This project addresses this challenge with the principal investigator's discovery that a binary solvent mixture of thiol and amine can readily dissolve a wide scope of bulk inorganic chalcogenide semiconductors to make solution processible semiconductor inks. This is notable because these materials are typically insoluble in common solvents. The benefits of this solvent system are four-fold: (i) it possesses high solvent power under ambient conditions, (ii) it is relatively nonhazardous, (iii) dissolution is kinetically fast, and (iv) it has sufficient volatility such that it is amenable to solution deposition. Upon solution deposition of the semiconductor ink, high-quality crystalline thin films of the target inorganic phases can be achieved under mild conditions. In this project, the principal investigator is leveraging his group's expertise in inorganic material synthesis to meet the following objectives: (i) Explore the scope of bulk materials that can be dissolved and solution processed with the thiol-amine solvent mixture. An emphasis is being placed on studying the mechanism of dissolution through an examination of the molecular solutes; (ii) Assess the solution-processed films by photoelectrochemical characterization techniques to gauge the utility of the semiconductor films for solar energy conversion. If certain requirements are met (e.g., strong induced photocurrent, band gap between ~1.0-1.5 eV, comprised of earth abundant elements), then first-generation solid-state solar cells are being fabricated and tested; and (iii) Apply the semiconductor inks toward the synthesis and ligand exchange of inorganic nanocrystals. These objectives will ultimately enable a "materials by design" approach to be taken, in which new functional thin films and nanocrystals can be rationally synthesized from bulk materials to meet specific applications.

非技术性总结：大规模制造低成本半导体薄膜有望改善包括太阳能电池在内的许多高科技应用。 高真空技术可以实现优异质量的半导体薄膜，但是低沉积速度、高成本、难以扩展和/或高处理温度可能是限制性的，这取决于特定的工艺和待沉积的材料。 概念上有吸引力的替代路线涉及前体溶液（或半导体油墨）的预形成，随后通过喷涂、卷对卷或丝网印刷或浸涂将油墨简单且廉价地溶液沉积到基底上。 这为半导体油墨的发展提供了强大的推动力;然而，大多数块状无机半导体在普通溶剂中完全不溶，使得通过简单溶解形成油墨非常困难。 这突出了对无机半导体的新的“通用溶剂”或碱的需求。 在材料研究部门的固态和材料化学计划的支持下，主要研究人员正在利用他的研究小组发现的一种新型溶剂混合物来溶解广泛的散装无机材料，以制造溶液可加工的半导体墨水。 在所得半导体油墨的溶液沉积后，研究小组证明可以使用温和的条件实现高质量的半导体薄膜。 纳入这项研究计划是一个外展计划，专门针对当地社区大学的学生。 社区大学的学生人口是传统化学推广计划中最不具针对性的;然而，更大的洛杉矶地区是美国社区大学学生人数最多的地区。 这个为期8周的年度外展计划的目的是为这些学生提供STEM研究机会，这是社区学院无法提供给他们的，从而提高他们到4年制院校的转学率。技术摘要：尽管在固态和材料化学领域已经发展了50多年，仍然只有有限数量的方法来沉积存款无机半导体薄膜-其中大多数需要苛刻和能量密集的条件。 该项目解决了这一挑战，主要研究者发现硫醇和胺的二元溶剂混合物可以容易地溶解大范围的散装无机硫属化物半导体，以制造溶液可加工的半导体墨水。 这是值得注意的，因为这些材料通常不溶于普通溶剂。 该溶剂系统的益处是四方面的：（i）其在环境条件下具有高溶剂力，（ii）其相对无害，（iii）溶解动力学快速，和（iv）其具有足够的挥发性，使得其适合于溶液沉积。 在溶液沉积半导体油墨时，可以在温和条件下获得目标无机相的高质量结晶薄膜。 在该项目中，主要研究者利用其小组在无机材料合成方面的专业知识来实现以下目标：（i）探索可以用硫醇-胺溶剂混合物溶解和溶液处理的散装材料的范围。 一个重点是放在研究溶解的机制，通过检查的分子溶质;（二）评估的解决方案处理的薄膜，通过光电化学表征技术，以衡量太阳能转换的半导体薄膜的效用。 如果满足某些要求（例如，强感应光电流，带隙在~1.0- 1.5eV之间，由地球丰富的元素组成），然后制造和测试第一代固态太阳能电池;和（iii）将半导体油墨应用于无机纳米晶体的合成和配体交换。 这些目标将最终使“材料的设计”的方法，其中新的功能薄膜和纳米晶体可以合理地合成从散装材料，以满足特定的应用。