A light-emitting device comprising: a flip-chip light-emitting diode semiconductor chip configured to provide a primary light; a photoluminescent structure disposed on the flip-chip LED semiconductor chip, but not covering a chip-edge surface of the flip-chip LED semiconductor chip, the photoluminescent structure comprising a first photoluminescent layer, an optically transparent isolation layer, a second photoluminescent layer, and an optically transparent moisture barrier layer, wherein: the first photoluminescent layer, comprising a first polymer matrix material and a lower-excitation-energy-level phosphor material dispersed within the first polymer matrix material, is disposed on a chip-upper surface of the flip-chip LED semiconductor chip; the optically transparent isolation layer is disposed on the first photoluminescent layer; the second photoluminescent layer, comprising a second polymer matrix material and a higher-excitation-energy-level quantum dot material dispersed within the second polymer matrix material, is disposed on the optically transparent isolation layer; and the optically transparent moisture barrier layer is disposed on the second photoluminescence layer; and a moisture-barrier reflective structure covering a photoluminescent-side surface of the photoluminescent structure and the chip-edge surface of the flip-chip LED semiconductor chip, but not covering a lower electrode surface of the flip-chip LED semiconductor chip, wherein: the moisture-barrier reflective structure comprises a third polymer matrix material and light scattering particles dispersed within the third polymer matrix material, and the third polymer matrix material has a water vapor transmission rate of not more than 20 g/(m 2 •day) at a thickness of 1 mm; and the lower-excitation-energy-level phosphor material of the first photoluminescent layer is configured to convert a portion of the primary light into a lower-energy-level visible light. a flip-chip light-emitting diode semiconductor chip configured to provide a primary light; a photoluminescent structure disposed on the flip-chip LED semiconductor chip, but not covering a chip-edge surface of the flip-chip LED semiconductor chip, the photoluminescent structure comprising a first photoluminescent layer, an optically transparent isolation layer, a second photoluminescent layer, and an optically transparent moisture barrier layer, wherein: the first photoluminescent layer, comprising a first polymer matrix material and a lower-excitation-energy-level phosphor material dispersed within the first polymer matrix material, is disposed on a chip-upper surface of the flip-chip LED semiconductor chip; the optically transparent isolation layer is disposed on the first photoluminescent layer; the second photoluminescent layer, comprising a second polymer matrix material and a higher-excitation-energy-level quantum dot material dispersed within the second polymer matrix material, is disposed on the optically transparent isolation layer; and the optically transparent moisture barrier layer is disposed on the second photoluminescence layer; and a moisture-barrier reflective structure covering a photoluminescent-side surface of the photoluminescent structure and the chip-edge surface of the flip-chip LED semiconductor chip, but not covering a lower electrode surface of the flip-chip LED semiconductor chip, wherein: the moisture-barrier reflective structure comprises a third polymer matrix material and light scattering particles dispersed within the third polymer matrix material, and the third polymer matrix material has a water vapor transmission rate of not more than 20 g/(m 2 •day) at a thickness of 1 mm; and the lower-excitation-energy-level phosphor material of the first photoluminescent layer is configured to convert a portion of the primary light into a lower-energy-level visible light. the moisture-barrier reflective structure comprises a third polymer matrix material and light scattering particles dispersed within the third polymer matrix material, and the third polymer matrix material has a water vapor transmission rate of not more than 20 g/(m 2 •day) at a thickness of 1 mm; and the lower-excitation-energy-level phosphor material of the first photoluminescent layer is configured to convert a portion of the primary light into a lower-energy-level visible light.