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With the discovery of more effective photocathode materials, which increased in both sensitivity and quantum efficiency, it became possible to achieve significant levels of gain over Generation 0 devices.

In 1936, the S-11 cathode ( cesium-antimony ) was discovered by Gorlich, which provided sensitivity of approximately 80 µA / lm with a quantum efficiency of around 20 %; this only included sensitivity in the visible region with a threshold wavelength of approximately 650 nm.