升阳太阳能技术股份有限公司美国存托凭证招股说明书（2026年6月26日版）

PROSPECTUS SUPPLEMENT(To Prospectus Dated December 30, 2025) Ascent Solar Technologies, Inc. We have entered into an at the market offering agreement (the “Offering Agreement”), dated May 16, 2024, with H.C.Wainwright& Co., LLC, as sales agent (the “Sales Agent” or “Wainwright”), relating to the sale of our common stock, par value$0.0001 per share, offered by this prospectus supplement and the accompanying base prospectus. In accordance with the terms of theOffering Agreement and this prospectus supplement and the accompanying base prospectus, we may offer and sell shares of our Sales of our common stock, if any, under this prospectus supplement and the accompanying base prospectus may be made byany method permitted by law deemed to be “at-the-market” offerings as defined in Rule 415 promulgated under the Securities Act of1933, as amended (the “Securities Act”), including, without limitation, sales made directly on or through the Nasdaq Capital Market(“Nasdaq”), the existing trading market for our common stock, or any other existing trading market in the United States for ourcommon stock, sales made to or through a market maker other than on an exchange or otherwise, directly to the Sales Agent asprincipal in negotiated transactions at market prices prevailing at the time of sale or at prices related to such prevailing market prices,and/or in any other method permitted by law. If we and Wainwright agree on any method of distribution other than sales of shares ofour common stock on Nasdaq or another existing trading market in the United States at market prices, we will file a further prospectussupplement providing all information about such offering as required by Rule 424(b) under the Securities Act. Wainwright is not Wainwright will be entitled to compensation at a fixed cash commission rate of 3.0% of the gross sales price of the shares soldby it under the Offering Agreement. In connection with the sale of common stock on our behalf, Wainwright will be deemed to be an“underwriter” within the meaning of the Securities Act and the compensation of Wainwright will be deemed to be underwritingcommissions or discounts. We provide more information about our compensation arrangements with the Sales Agent in the sectionentitled “Plan of Distribution.” We have also agreed to provide indemnification and contribution to Wainwright with respect to certain Our common stock is listed on Nasdaq under the symbol “ASTI.” On June 25, 2026, the last reported sale price of our commonstock on Nasdaq was $4.97 per share. Investing in our common stock involves a high degree of risk. See “Risk Factors” beginning on pageS-6of thisprospectus supplement, page 2 of the accompanying prospectus and under similar headings in the documents incorporated by Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved ofthese securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Anyrepresentation to the contrary is a criminal offense. H.C. Wainwright& Co. The date of this prospectus supplement is June 26, 2026. ABOUT THIS PROSPECTUS SUPPLEMENT This prospectus supplement and the accompanying base prospectus form a part of a registration statement on FormS-3(FileNo.333-291104),which was declared effective on December 30, 2025, that we filed with the Securities Exchange Commission(“SEC”) utilizing a “shelf’ registration process. Under the shelf registration process, we may offer and sell shares of our common stockhaving an aggregate offering price of up to $100,000,000 from time to time, and, specifically, under this prospectus supplement we This document is in two parts. The first part is the prospectus supplement, which describes the specific terms of this offering.The second part, the accompanying base prospectus, provides more general information about the securities we may offer from time totime, some of which may not apply to the securities offered by this prospectus supplement. Generally, when we refer to thisprospectus, we are referring to both parts of this document combined. Before you invest, you should carefully read this prospectussupplement, the accompanying base prospectus, all information incorporated by reference herein and therein, any free writingprospectus that we may authorize for use in connection with this offering, and the additional information described under “Where YouCan Find More Information” in this prospectus supplement. These documents contain information you should consider when makingyour investment decision. This prospectus supplement may add, update or change information contained in the accompanying base You should rely only on the information contained or incorporated herein by reference in this prospectus supplement and in anyfree writing prospectus that we may authorize for use in connection with this offering and contained or incorporated therein byreference in the accompanying base pr