Dopant-Assisted Crystallization Enables Germanium Quantum Dots with Enhanced Product Yields and Optoelectronic Properties

Colloidal germanium quantum dots (GeQDs) show great potential for optoelectronics, but traditional synthesis methods face challenges such as low yield and uneven particle sizes due to Ge sublimation and domain overgrowth at high temperatures. This study introduces a dopant-assisted synthesis method that enhances the crystallization process of GeQDs. By incorporating cobalt dopants into sol–gel precursors, we have effectively reduced the GeQD formation temperature to 350 °C. This approach boosts product yield over 60%, a 3.6-fold increase over conventional methods. The resulting GeQDs exhibit uniform particle sizes, enhanced solution processability, and improved charge carrier mobilities. We further constructed the GeQD-based solar cells that demonstrate an AM1.5 solar power conversion efficiency of 3.5 × 10 –5 % with a 0.83 V open-circuit voltage.