A display module comprising: a cover glass sized larger than an active display area of the display module; a thin-film transistor, TFT, backplane with a first side and an opposing second side, wherein the TFT backplane has: an array of display pixel circuits located on the first side, and an array of sensor pixel circuits located on the first side, each sensor pixel circuit configured to form part of a piezoelectric ultrasonic fingerprint sensor circuit for a piezoelectric ultrasonic fingerprint sensor , wherein the array of display pixel circuits and the array of sensor pixel circuits occupy non-overlapping areas of the TFT backplane ; one or more display components positioned between the cover glass and the TFT backplane , the one or more display components configured to, in conjunction with the array of display pixel circuits, provide display functionality for the display module, wherein at least part of the piezoelectric ultrasonic fingerprint sensor is located between the TFT backplane and the cover glass ; wherein the piezoelectric ultrasonic fingerprint sensor-related components located between the backplane and the cover glass have an overall thickness that is less than the gap distance between the cover glass and the TFT backplane ; one or more layers of spacer glass or other material, said material configured to prevent or reduce acoustic impedance mismatches between materials as the ultrasonic wave travels towards the exposed surface of the cover glass, interposed between the piezoelectric ultrasonic fingerprint sensor and the cover glass such that there are no free gaps between the piezoelectric ultrasonic fingerprint sensor and the cover glass . a cover glass sized larger than an active display area of the display module; a thin-film transistor, TFT, backplane with a first side and an opposing second side, wherein the TFT backplane has: an array of display pixel circuits located on the first side, and an array of sensor pixel circuits located on the first side, each sensor pixel circuit configured to form part of a piezoelectric ultrasonic fingerprint sensor circuit for a piezoelectric ultrasonic fingerprint sensor , wherein the array of display pixel circuits and the array of sensor pixel circuits occupy non-overlapping areas of the TFT backplane ; an array of display pixel circuits located on the first side, and an array of sensor pixel circuits located on the first side, each sensor pixel circuit configured to form part of a piezoelectric ultrasonic fingerprint sensor circuit for a piezoelectric ultrasonic fingerprint sensor , wherein the array of display pixel circuits and the array of sensor pixel circuits occupy non-overlapping areas of the TFT backplane ; one or more display components positioned between the cover glass and the TFT backplane , the one or more display components configured to, in conjunction with the array of display pixel circuits, provide display functionality for the display module, wherein at least part of the piezoelectric ultrasonic fingerprint sensor is located between the TFT backplane and the cover glass ; wherein the piezoelectric ultrasonic fingerprint sensor-related components located between the backplane and the cover glass have an overall thickness that is less than the gap distance between the cover glass and the TFT backplane ; one or more layers of spacer glass or other material, said material configured to prevent or reduce acoustic impedance mismatches between materials as the ultrasonic wave travels towards the exposed surface of the cover glass, interposed between the piezoelectric ultrasonic fingerprint sensor and the cover glass such that there are no free gaps between the piezoelectric ultrasonic fingerprint sensor and the cover glass . <EOS>