Ultrahigh-Working-Frequency Embedded Supercapacitors with 1T Phase MoSe ₂ Nanosheets for System-in-Package Application

Commercial aluminium electrolyte capacitors (AECs) are too large for integration in future highly integrated electronic systems. Supercapacitors, in comparison, possess a much higher capacitance per unit volume and can be embedded as passive capacitors to address such challenges in electronics scaling. However, the slow frequency response (<10 ¹ Hz) typical of supercapacitors is a major hurdle to their practical application. Here, it is demonstrated that 1T-phase MoSe ₂ nanosheets obtained by laser-induced phase transformation can be used as an electrode material in embedded micro-supercapacitors. The metallic nature of MoSe ₂ nanosheet-based electrodes provides excellent electron- and ion-transport properties, which leads to an unprecedented high-frequency response (up to 10 ⁴ Hz) and cycle stability (up to 10 ⁶ cycles) when integrated in supercapacitors, and their power density can be ten times higher than that of commercial AECs. Furthermore, fabrication processes of the present device are fully compatible with system-in-package device manufacturing to meet stringent specifications for the size of embedded components. The present research represents a critical step forward in in-package and on-chip applications of electrolytic capacitors.