text: *Ag-O-Cs, also called S-1. This was the first compound photocathode material, developed in 1929. Sensitivity from 300 nm to 1200 nm. Since Ag-O-Cs has a higher dark current than more modern materials, photomultiplier tubes with this photocathode material are nowadays used only in the infrared region with cooling. 
  *Sb-Cs (antimony-caesium) has a spectral response from UV to visible and is mainly used in reflection-mode photocathodes. 
  *Bialkali (antimony-rubidium-caesium Sb-Rb-Cs, antimony-potassium-caesium Sb-K-Cs). Spectral response range similar to the Sb-Cs photocathode, but with higher sensitivity and lower dark current than Sb-Cs. They have sensitivity well matched to the most common scintillator materials and so are frequently used for ionizing radiation  measurement in scintillation counters. 
  *High temperature bialkali or low noise bialkali (sodium-potassium-antimony, Na-K-Sb). This material is often used in oil well logging since it can withstand temperatures up to 175 °C. At room temperatures, this photocathode operates with very low dark current, making it ideal for use in photon counting applications. 
  *Multialkali (sodium-potassium-antimony-caesium, Na-K-Sb-Cs), also called S-20.  The multialkali photocathode has a wide spectral response from the ultraviolet to near infrared region. It is widely used for broad-band spectrophotometers and photon counting applications. The long wavelength response can be extended to 930 nm by a special photocathode activation processing. With the broadened response, this is sometimes referred to as S-25.
  *GaAs (gallium(II) arsenide). This photocathode material covers a wider spectral response range than multialkali, from ultraviolet to 930 nm. GaAs photocathodes are also used in accelerator facilities where polarized electrons are required. One of the important property of GaAs photocathode is, it can achieve Negative Electron Affinity due to Cs deposition on the surface. However GaAs is very delicate and loses Quantum Efficiency(QE) due to couple of damage mechanism. Ion Back Bombardment is one of the main cause of GaAs cathode QE decay.
  *InGaAs (indium gallium arsenide). Extended sensitivity in the infrared range compared to GaAs. Moreover, in the range between 900 nm and 1000 nm, InGaAs has a much better signal-to-noise ratio than Ag-O-Cs. With special manufacturing techniques this photocathode can operate up to 1700 nm. 
  *Cs-Te, Cs-I (caesium-telluride, caesium iodide). These materials are sensitive to vacuum UV and UV rays but not to visible light and are therefore referred to as solar blind. Cs-Te is insensitive to wavelengths longer than 320 nm, and Cs-I to those longer than 200 nm.