Spatial confined hot carrier dynamics for beyond unity quantum efficiency detection

Photon harvesting and conversion in semiconductors hold critical scientific and technological value due to their wide-ranging applications, including optoelectronics, renewable energy, and thermal management. However, the efficiency of optical-to-electrical energy conversion is fundamentally limited by the rapid relaxation of thermalized carriers. Here, we demonstrate a spatial confinement-controlled hot carrier dynamics in a T-shape lead selenide photo-thermoelectric device, which achieves a room temperature external quantum efficiency values exceeding unity. This enhancement arises from spatial confinement-induced local phonon scattering, which suppresses the optical-excited hot carrier relaxation. As a result, the T-shape lead selenide detector achieves a room temperature peak detectivity of 6.3 × 10¹⁰ cm Hz^1/2 W^-1 beyond thermoelectric theoretical limit. This work establishes a transformative pathway for achieving high-efficiency photodetection and energy conversion technologies.