Energy
transfer (ET) of trivalent rare earth (RE)-doped inorganic
crystals has been investigated comprehensively from theory to technology;
however, the influence of photocarrier transmission has been considered
impossible, as the 4f electrons of RE ions are shielded well from
outer electrons. Here, on the basis of an anisotropic Bi3O4Cl layered semiconductor, we report for the first time
the ET phenomenon of an Er3+–Yb3+ codoped
system locked by photocarrier separation. When the photocarrier of
the layered host is separated efficiently under a vertical spontaneous
interelectric field, the ET and energy-back-transfer (EBT) between
Er3+ and Yb3+ ions can be inhibited completely;
otherwise, they can occur as usual. Consequently, the Yb3+ ion dopant mainly acts as a quencher for 980 nm-excited visible
upconversion (UC) and infrared emission of Er3+ ions, and
the cross-relaxation between Er3+ and Yb3+ ions
via EBT is inhibited simultaneously. We show that the separated photoholes
on the surface can suppress the recombination of excited electrons
of Er3+ ions to the ground level, leading to a special
“electron jam” on intermediate levels, which prevents
the acceptance of excited electrons further via either the ET or EBT
process. The result of our current work greatly enhances the understanding
of ET behavior of RE ions and the material structure of RE-doped materials.