Suppressed Trap Density Leads to Versatile p-i-n Heterojunction Photodiode with Enhanced Photovoltaic/Photodetection Dual-Function

Multifunctional integration of optoelectronic devices within a single photodiode is in high demand for next-generation on-chip multifunctional integration and Internet of Things applications. Owing to the rapidity of nucleation-crystallization that is associated with the solution method, large trap state densities (N_t), and consequently, severe dark current densities, as well as recombination losses are generally induced, which are detrimental to the detectivity (D*) of organic photodetectors (OPDs) and to the open-circuit voltage (V_OC) of organic photovoltaics (OPVs). Herein, a versatile p-i-n heterojunction organic photodiode with optimized vertical phase distribution and rational solid-state packing is fabricated via a layer-by-layer (LBL) deposition procedure entailing the introduction of a rylene-fullerene hybrid as a morphological modulator. This precisely controlled photodiode displayed suppressed N_t (2.5 × 10¹⁶ cm⁻³), low-lying Urbach energy E_u (23.2 meV), as well as synergistically reduced series resistance, dark current, and sub-bandgap radiative/non-radiative recombination losses. Consequently, this ternary-pseudo-bilayer-type photodiode exhibits excellent dual-function performance with an outstanding D* of 9.48 × 10¹¹ Jones in self-powered OPD mode and a surprisingly suppressed energy loss of 0.538 eV in OPV mode. This study provides important insights into the mechanism and effects of trap density and energy disorder suppression in solution-processed multifunctional integrated photoelectric conversion diodes.