Electric-field Quantum Sensing Exploiting a Photogenerated Charge-transfer Triplet State in a Molecular Semiconductor

TL;DR

This paper demonstrates a novel method for electric field sensing using a photogenerated charge-transfer triplet state in an organic molecule, achieving high sensitivity without relying on atomic spin-orbit coupling.

Contribution

It introduces a new organic molecular system for electric field sensing that combines coherent control with strong directional sensitivity, bypassing the need for heavy atoms.

Findings

SEC strength of 0.51 Hz/(V/m) measured

Electric field sensitivity comparable to atomic SOC systems

Organic CT triplets enable chemically versatile quantum sensing

Abstract

Molecular spin systems are promising platforms for quantum sensing due to their chemically tunable Hamiltonians, enabling tailored coherence properties and interactions with external fields. However, electric field sensing remains challenging owing to typically weak spin-electric coupling (SEC) and limited directional sensitivity. Addressing these issues using heavy atoms exhibiting strong atomic spin-orbit couplings (SOC) often compromises spin coherence times. Here, we demonstrate coherent electric field sensing using a photogenerated charge-transfer (CT) spin triplet state in the organic molecule ACRSA (10-phenyl-10H,10' H-spiro\[acridine-9,9'-anthracen]-10'-one). By embedding electric field pulses within a Hahn echo sequence, we coherently manipulate the spin triplet and extract both the magnitude and directional dependence of its SEC. The measured SEC strength is approximately 0.51 Hz/(V/m), comparable to values reported in systems with strong atomic SOC, illustrating that heavy atoms are not a prerequisite for electric-field sensitivity of spin states. Our findings position organic CT triplets as chemically versatile and directionally sensitive quantum sensors of E-fields that function without atomic-SOC-mediated mechanisms.