[3] Tl2S can be prepared from the elements or by precipitating the sulfide from a solution of thallium(I), e.g. the sulfate or nitrate.

Thin films have been deposited, produced from a mixture of citratothallium complex and thiourea.

Heating the film in nitrogen at 300°C converts all the product into Tl2S [4] This salt was used in some of the earliest photo-electric detectors by Theodore Case who developed the so-called thalofide (sometimes spelt thallofide) cell, used in early film projectors.

Case's work was then built on by R.J. Cashman who recognised that the controlled oxidation of the Tl2S film was key to the operation of the cell.

[6] Cashman's work culminated in the development of long wave infrared detectors used during the Second World War.