A display may have a thin-film transistor layer and color filter layer. The display may have an active area and an inactive border area. Light blocking structures in the inactive area may prevent stray backlight from a backlight light guide plate from leaking out of the display. The thin-film transistor layer may have a clear substrate, a patterned black masking layer on the clear substrate, a clear planarization layer on the black masking layer, and a layer of thin-film transistor circuitry on the clear planarization layer. The black masking layer may be formed from black photoimageable polyimide. The clear planarization layer may be formed from spin-on glass. The light blocking structures may include a first layer formed from a portion of the black masking layer and a second layer such as a layer of black tape on the underside of the color filter layer.