# Tuning the effective spin-orbit coupling in molecular semiconductors

## TL;DR

This study systematically links the g-tensor shift in molecular semiconductors to the effective spin-orbit coupling strength, revealing how molecular structure influences spin relaxation and enabling better control of spin properties in organic electronics.

## Contribution

It provides a direct correlation between g-tensor shifts and SOC strength in high mobility molecular semiconductors, advancing understanding of spin relaxation mechanisms in organics.

## Key findings

- g-shifts vary with molecular composition and structure
- Spin-lattice relaxation times span four orders of magnitude
- Correlation established between g-shifts and relaxation times

## Abstract

The control of spins and spin to charge conversion in organics requires understanding the molecular spin-orbit coupling (SOC), and a means to tune its strength. However, quantifying SOC strengths indirectly through spin relaxation effects has proven diffi- cult due to competing relaxation mechanisms. Here we present a systematic study of the g-tensor shift in molecular semiconductors and link it directly to the SOC strength in a series of high mobility molecular semiconductors with strong potential for future devices. The results demonstrate a rich variability of the molecular g-shifts with the effective SOC, depending on subtle aspects of molecular composition and structure. We correlate the above g -shifts to spin-lattice relaxation times over four orders of magnitude, from 200 {\mu}s to 0.15 {\mu}s, for isolated molecules in solution and relate our findings for isolated molecules in solution to the spin relaxation mechanisms that are likely to be relevant in solid state systems.