Abstract <p>Quantum-dot Cellular Automata (QCA) offers a paradigm shift from CMOS by leveraging quantum confinement and electron tunneling for ultra-low-power nanocomputing. This technology enables the creation of sequential digital circuits without transistors, utilizing cell polarization for both logic and data storage. This paper addresses the lack of reset-enabled flip-flops and dedicated decimal counters in QCA by proposing a novel T flip-flop with integrated asynchronous reset functionality, optimized from a baseline design to achieve highly polarized outputs and high energy efficiency. Based on this design, the first-ever QCA-based asynchronous Binary-Coded Decimal (BCD) counter is introduced, reducing cell count by 30.4% compared to existing 4-bit counters, using 61.8% less energy, and employing multilayer crossovers for full input-output accessibility and zero crosstalk. The design ensures scalability and thermal stability, making it ideal for applications like digital clocks and biomedical devices. This work bridges critical gaps in QCA sequential logic, providing a foundation for future nano-IC fabrication and complex decimal-based systems.</p>