(color online) (a) The contour plots of PL spectra as a function of magnetic field at different bias voltages with pumping power of 7.11 μ W [(a1)–(a5)] and 11.85 μ W [(a6)–(a10)]. With the increasing bias voltages and pumping power, additional weak peaks appear with strong diamagnetic shifts in the magnetic field. The peaks with normal, ‘positive’, and ‘negative’ diamagnetic coefficients are marked with black squares, green triangles, and red circlesas labeled on panel (a10). In addition, the right figure shows the enlarged anti-crossing of X³⁻ exciton. (b) The calculated diamagnetic coefficients of different charge states in a coupled system at a pumping power of 11.85 μW and a bias voltage of +0.5 V. (c) Schematic energy diagrams of the initial and final states of negatively charged exciton states in the coupled QD-wetting layer system. When the electrons in the wetting layer recombine with holes in the QD, resulting in large positive diamagnetic shifts, while when electrons in the QD recombine with the holes in the QD, owing to the absence of attraction of the holes in the QD after recombination, the electrons in the wetting layer spread in the final states and large wavefunction distribution differences between the initial and final states are formed, resulting in a negative diamagnetic effect.^[23]