First-principles perspective on full-spectrum infrared photodetectors from doping an excitonic insulator

TL;DR

This paper introduces a novel infrared photodetector concept based on doping excitonic insulators, demonstrating tunable detection capabilities from terahertz to near-infrared using first-principles calculations on a one-dimensional organometallic wire.

Contribution

It proposes a new design for infrared photodetectors utilizing the negative exciton transition energy in excitonic insulators, with tunability demonstrated through first-principles calculations.

Findings

Doping can tune exciton transition energy from 0 to 0.6 eV.

The proposed detectors offer high wavelength selectivity and thermal stability.

The work expands the family of excitonic insulators and suggests new avenues for infrared detection.

Abstract

Innovations in imaging technology involves finding strategies and materials suitable for detection applications over the entire infrared range. Herein, we propose a new design concept based on the unique feature of an excitonic insulator, namely, negative exciton transition energy ($E_t$). We demonstrate this concept using first-principles $GW$-BSE calculations on one-dimensional organometallic wire (CrBz)$_\infty$. The pristine (CrBz)$_\infty$ exhibits an excitonic instability due to a negative $E_t$ for the lowest exciton. Substitutional doping can continuously tune the $E_t$ from $\sim$0 to $\sim$0.6 eV, which shows the ability of photon detection from terahertz to near-infrared. This type of detectors have advantages of outstanding wavelength selectivity, reduced thermal disturbance and elevated working temperature. Our work not only adds another member in the family of rare one-dimensional excitonic insulators, but also opens a new avenue for the development of high-performance infrared photodetectors in the future.