量子效率（英语：Quantum efficiency，常缩写为 QE）是用来定义光敏器件，例如底片、感光耦合组件（英语：charge-coupled device，CCD）将其受光表面接收到的光子转换为电子-空穴对的百分比例，即

量子效率是组件对光敏感性的精确测量。由于光子的能量与波长的倒数成比例，量子效率的测量通常是在一段波长范围内进行。底片的量子效率通常少于10%，而感光耦合组件在某些波长位置具有超过90%的效率。

The term quantum efficiency (QE) may apply to incident photon to converted electron (IPCE) ratio, of a photosensitive device or it may refer to the TMR effect of a Magnetic Tunnel Junction.

This article deals with the term as a measurement of a device's electrical sensitivity to light. In a charge-coupled device (CCD) it is the percentage of photons hitting the device's photoreactive surface that produce charge carriers. It is measured in electrons per photon or amps per watt. Since the energy of a photon is inversely proportional to its wavelength, QE is often measured over a range of different wavelengths to characterize a device's efficiency at each photon energy level. The QE for photons with energy below the band gap is zero. Photographic film typically has a QE of much less than 10%, while CCDs can have a QE of well over 90% at some wavelengths.