Improved cells retained efficiency (IMAGE) City University of Hong Kong Caption By introducing a thermally robust charge extraction layer, the improved cells retain over 90% of their efficiency, even after prolonged exposure (over 1,200 hours) to high temperatures, around (65℃). Credit Prof. Zhu Zonglong’s research group / City University of Hong Kong Usage Restrictions Image must be used with appropriate caption and credit. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.