OLED display substrate, method of forming the same and display device

An Organic Light-emitting Diode (OLED) display substrate, comprising:

• a driving thin film transistor located on a base substrate and configured to drive an OLED light-emitting unit to emit light;
• a photosensitive thin film transistor located on the base substrate and configured to be capable of detecting light emitted by the OLED light-emitting unit and generating an electrical signal, wherein at least a part of film layers of the photosensitive thin film transistor and at least a part of film layers of the driving thin film transistor are disposed at a same layer and made of a same material;
• and
• a second light-shielding pattern located at a side of an active layer of the driving thin film transistor away from the base substrate,
• wherein a gate electrode of the photosensitive thin film transistor and a first light-shielding pattern of the driving thin film transistor are disposed at a same layer and made of a same material, and the first light-shielding pattern is between an active layer of the driving thin film transistor and the base substrate, and
• wherein an orthographic projection of the active layer of the driving thin film transistor onto the base substrate is within an area of orthographic projections of the first light-shielding pattern and the second light-shielding pattern onto the base substrate, and the orthographic projection of the first light-shielding pattern onto the base substrate is within the orthographic projection of the second light-shielding pattern onto the base substrate.