  The advent of natural language processing and large language models (LLMs)
has revolutionized the extraction of data from unstructured scholarly papers.
However, ensuring data trustworthiness remains a significant challenge. In this
paper, we introduce PropertyExtractor, an open-source tool that leverages
advanced conversational LLMs like Google gemini-pro and OpenAI gpt-4, blends
zero-shot with few-shot in-context learning, and employs engineered prompts for
the dynamic refinement of structured information hierarchies - enabling
autonomous, efficient, scalable, and accurate identification, extraction, and
verification of material property data. Our tests on material data demonstrate
precision and recall that exceed 95\% with an error rate of approximately 9%,
highlighting the effectiveness and versatility of the toolkit. Finally,
databases for 2D material thicknesses, a critical parameter for device
integration, and energy bandgap values are developed using PropertyExtractor.
Specifically for the thickness database, the rapid evolution of the field has
outpaced both experimental measurements and computational methods, creating a
significant data gap. Our work addresses this gap and showcases the potential
of PropertyExtractor as a reliable and efficient tool for the autonomous
generation of various material property databases, advancing the field.
