Non-carrier-injection　light-emitting　diodes　(NCI-LEDs)　are　expected　to　be　widely　used　in　the　next-generation　micro-display　technologies,　including　Micro-LEDs　and　nano-pixel　light-emitting　displays　due　to　theirsimple　device　structures.　However,　because　there　is　no　external　charge　carrier　injection,　the　internal　carriertransport　behavior　of　the　NCI-LED　cannot　be　described　by　using　the　traditional　PN　junction　and　LED　theory.Therefore,　establishing　a　carrier-transport　model　for　the　NCI-LED　is　of　great　significance　in　understanding　itsworking　mechanism　and　improving　device　performance.　In　this　work,　carrier　transport　mathematical　model　ofthe　NCI-LED　is　established　and　the　mechanical　behavior　of　charge-carrier　transport　is　analyzed　quantitatively.Based　on　the　mathematical　model,　the　working　mechanism　of　the　NCI-LED　is　explained,　the　carrier　transportcharacteristics　of　the　device　are　obtained.　Additionally,　the　key　features,　including　the　length　of　the　inducedcharge　region,　the　forward　biased　voltage　across　the　internal　PN　junction,　and　the　reverse　biased　voltage　acrossthe　internal　PN　junction　are　studied.　Their　relationships　with　the　applied　frequency　of　the　applied　drivingvoltage　are　revealed.　It　is　found　that　both　the　forward　bias　and　reverse　bias　of　the　internal　PN　junction　increasewith　the　driving　frequency.　When　the　driving　frequency　reaches　a　certain　value,　the　forward　bias　and　thereverse　bias　of　the　PN　junction　will　be　maintained　at　a　maximum　value.　Moreover,　the　length　of　the　inducedcharge　region　decreases　with　the　increase　of　the　driving　frequency,　and　when　the　frequency　reaches　a　certainvalue,　the　induced　charge　region　will　always　be　in　the　state　of　exhaustion.　According　to　the　mathematicalmodel,　suggestions　for　the　device　optimization　design　are　provided　below.　1)　Reducing　the　doping　concentrationof　the　induced　charge　region　can　effectively　increase　the　voltage　drop　across　the　internal　LED;　2)　employing　thetunneling　effect　occurring　in　the　reverse-biased　PN　junction　can　effectively　improve　the　electroluminescenceintensity;　3)　using　the　square-wave　driving　voltage　can　obtain　a　larger　voltage　drop　across　the　internal　LED　andincrease　the　electroluminescence　intensity.　This　work　on　the　carrier　transport　model　is　expected　to　e　present　aclear　physical　figure　for　understanding　the　working　mechanism　of　NCI-LED,　and　to　provide　a　theoreticalguidance　for　optimizing　the　device　structure.