Assertion: led's efficiency | /r/HasProperty | limited to a few %
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text: Indirect bandgap materials like GaP were still developed for green and red emitters, with many applications, e.g., in indoor alphanumeric displays, but the efficiencies (as emitted light power per input electrical power) were limited to about 1% in green (N-doped GaP) and a few % in red (Zn-, O-doped GaP)