Photovoltage-Driven Two-Transistor-One-Diode Perovskite Pixels for In-Cell Optical Sensing Displays.

Abstract

In-cell optical sensing displays are essential for next-generation interactive electronics, yet conventional architectures rely on separate light-emitting diodes (LEDs) and photodetectors (PDs), limiting pixel density and efficiency. Achieving both functions within a single diode is intrinsically difficult because electroluminescence requires strong excitonic recombination, whereas photodetection benefits from efficient carrier separation. Here, we realize stable dual-mode operation by stabilizing intermediate-n quasi-2D phases and suppressing non-radiative losses with a fluorinated acid passivator, and by engineering high-mobility transport layers with a dissociative (type-II) perovskite/electron transport layer heterojunction to assist exciton dissociation under photovoltaic operation. The resulting bifunctional diode enables an opto-dynamic random-access memory (opto-DRAM) pixel, a two-transistor-one-diode (2T1D) architecture conceptually analogous to a two-transistor-one-capacitor (2T1C) DRAM gain-cell, where photovoltage-driven rather than photocurrent-driven detection enables self-amplified sensing when coupled to thin-film transistors. The sky-blue PeLED achieves an external quantum efficiency of 20.4% at 100 cd m^-2 and a record power efficiency of 41.8 lm W^-1, while as the coupled sensing pixel it exhibits a maximum responsivity of 4.17 × 10⁴ A W^-1 and a specific detectivity of 6.46 × 10¹³ Jones. Monolithic integration yields an active-matrix display capable of switchable emission and imaging functions offering a scalable platform for compact, energy-efficient, and multifunctional optoelectronics.