Work Function Tuning for High‐Performance Solution‐Processed Organic Photodetectors with Inverted Structure

Abstract

Organic photodetectors with inverted structure are fabricated by solution process techniques. A very thin interfacing layer of polyethyleneimine leads to a homogenous interface with low work function. The devices exhibit excellent performances, in particular in terms of low dark current density, wide range linearity, high detectivity, and remarkable stability in ambient air without encapsulation.

Organic Photodiodes: The Future of Full Color Detection and Image Sensing

“…While many molecular materials are processed by evaporation, [ 105 ] there are examples whereby they are solution processed. [ 37,106 ] Macromolecules such as dendrimers and polymers can be processed from solution using techniques such as aerosol-jet printing, [ 107 ] spin-coating, [ 108 ] inkjet-printing, [ 109,110 ] screen printing, [ 111 ] or spray-coating. [112][113][114][115] …”

“…Specifi c detectivities as high as 10 13 J in the visible have been reported using organic semiconductors by suppressing the dark current and employing hole blocking layers. [ 95,108,126 ] The EQE can however be increased to larger values in the presence of gain and photo-multiplication. Guo et al have reported using poly(3-n -hexylthiophene) (P3HT, B1 , see Figure 5 ) and poly(9-vinylcarbazole) (PVK, B2 ) blended with zinc oxide (ZnO) nanoparticles (NP) to increase the gain in order to obtain an EQE 10…”

Efficiency improved for inverted polymer solar cells with electrostatically self-assembled BenMeIm-Cl ionic liquid layer as cathode interface layer

“…To date, a variety of cathode interfacial materials have been applied to shift and modify the energy level of the ITO electrode, such as metal oxides (TiO 2 , ZnO), metal carbonates (Cs 2 CO 3 ) [9][10], titanium chelate (TIPD, TOPD) [12] and water/alcohol soluble polyelectrolytes (PEI, PFN) [4,[13][14][15][16][17]. However, IPSCs using metal oxides typically require a high annealing temperature (over 2001 C) to yield a high charge carrier mobility; the use of water/alcohol soluble polyelectrolytes creates a critical problem in the large-scale printing processes of IPSCs.…”

Low dark current inverted organic photodetectors employing MoO x :Al cathode interlayer

“…Considerable efforts have been devoted to reduce the dark 56 current of OPDs mainly by means of the insertion of additional 57 interfacial layers and the thickness modulation of the light 58 absorbing layer, leading to low dark current density (J d ) in the 59 range of 1-10 nA/cm 2 and the consequently high D ⁄ over 60 10 12 Jones [6][7][8][9][10][11]. 61 While most investigations have been carried out based on the 62 normal OPD structure, rather less attention [12][13][14] has been given 63 to the inverted geometry for OPDs, in which the layer sequence is 64 reversed and electrons are collected via the bottom electrode of the 65 OPD, facilitating its integration with a low work function metal-66 lization in TFT or CMOS circuits for hybrid imagers [4,12,13]. 67 Since a wide range of inverted structures have been already 68 applied to organic photovoltaics (OPVs) [15][16][17], it seems that 69 deriving relevant device geometries (i.e., interfacial buffer layers) 70 from inverted OPVs enables easier approach to make high quality 71 inverted OPDs.…”