Charge Generation in Doped Organic p–n Junctions: A Two‐Descriptor Design Framework

ABSTRACT

Charge‐generation layers (CGLs) underpin tandem organic optoelectronics, yet their host–dopant selection remains largely empirical, lacking a mechanism‐resolved descriptor for comparing candidate systems. Here, a temperature‐dependent reverse‐bias transport framework is established for a doped organic p–n junction composed of ReO ₃ ‐doped 4,4′,4″‐tris[2‐naphthyl(phenyl)amino]triphenylamine and Rb ₂ CO ₃ ‐doped 4,7‐diphenyl‐1,10‐phenanthroline. The doped junction sustains reverse current densities approximately three orders of magnitude higher than an undoped control, confirming dopant‐enabled charge generation and transport. Coupling Poole–Frenkel (PF) emission with thermally assisted dopant‐mediated tunneling (TAT) reproduces the reverse‐bias current density–voltage characteristics from 150 to 300 K, and resolves a temperature‐driven crossover from PF‐dominated hopping to TAT near room temperature. Notably, this competition reduces to two physically interpretable descriptors, the hopping activation parameter W and the effective energy offset φ _a , from which a W– φ _a design map is constructed, linking effective transport descriptors to the reverse‐bias voltage required for a target current density. This descriptor‐based framework reframes CGL host–dopant selection from empirical optimization toward mechanism‐guided materials design.