High-Performance Photomultiplication Photodiode with a 70 nm-Thick Active Layer Assisted by IDIC as an Efficient Molecular Sensitizer

Abstract

Here, a smart strategy for decreasing the active layer thickness of the organic photodiode down to 70 nm is demonstrated by utilizing a trap-assisted photomultiplication mechanism with the optimized chemical composition. Despite the presence of a high dark current, dramatically enhanced external quantum efficiency (EQE) via photomultiplication can allow significantly reduced active layer thickness, yielding high detectivity comparable to that of conventional Si. To achieve this, a spatially confined and electrically isolated optical sensitizer, 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno­[1,2-b:5,6-b′]­dithiophene-2,7-diyl)­bis­(methanylylidene))­bis­(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))­dimalononitrile (IDIC) was introduced strategically between a hole transport active layer and a cathode. A nonfullerene acceptor, IDIC, turned out to be a much more efficient sensitizer than the conventional fullerene-based acceptors, as confirmed by the effective lowering of the Schottky barrier under illumination, as well as the highest EQE exceeding 130 000%. Due to its favorable electronic structure as well as two-dimensional molecular structure, a high detectivity over 1012 Jones was successfully demonstrated while maintaining the active layer thickness as 70 nm.

Superior Noise Suppression, Response Time, and Device Stability of Non‐Fullerene System over Fullerene Counterpart in Organic Photodiode

“…The detectivity obtained in this work is the highest among the specific detectivity values of the non-fullerene acceptor-based OPDs reported to date ( Figure S10, Table S4, Supporting Information). [41][42][43][44][45][46][47][48][49] It is important to emphasize that most of the reported OPDs utilizing the non-fullerene acceptors have demonstrated detectivity calculated at a low applied bias voltage. Moreover, they show a relatively high dark current when a bias lower than −1 V is applied.…”

Recent Progress on Broadband Organic Photodetectors and their Applications

“…Latterly, Jang et al achieved high EQE in the PHJ-OPDs with ultrathin active layer by introducing narrow bandgap small molecular acceptor 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′] dithiophene-2,7-diyl)bis(methanylylidene)) bis(3-oxo-2,3-dihyd ro-1H-indene-2,1-diylidene))dimalononitrile (IDIC) as an optical sensitizer. [105] The PM-OPDs with 70 nm thick P3HT/IDIC PHJ exhibit broadband response from 300 to 750 nm with maximum EQE of 60 700% at −19 V bias. This work opens the possibility of ultrathin photodiode pixels, which can dramatically enhance the degree-of-integration of image sensors.…”

Interfacial electrostatic interaction-enhanced photomultiplication for ultra-high external quantum efficiency of organic photodiodes

“…Recently, research regarding photomultiplication-type organic photodiodes (PM-OPDs) with external quantum efficiencies (EQEs) exceeding 100% have been actively conducted 1,2,3,4,5,6,7,8,9,10 . Because the main application fields of OPDs are expanding not only to cameras, but also to finger/vein/iris recognition sensors and bio-signal sensors, which are operated primarily by weak light sources, PM-OPD can be a promising candidate for the commercialization of OPDs based on their self-signal amplification behavior.…”