Fine-Tuning Contact via Complexation for High-Performance Organic Solar Cells

Abstract

For organic optoelectronic devices, precise tuning of the electrical property of both active layers and interfaces is crucial to achieve enhanced device performance. Here we develop a facile method using complexation to modify the work function and energy levels of cathode contact layers in organic solar cells (OSCs) to achieve suitable work function/energy levels while retaining relatively good conductivity. Compared to the control devices with neat (N, N-dimethyl-ammonium N-oxide) propyl perylene diimide (PDINO) contacts, the tris(pentafluorophenyl) borane (BCF) complexed PDINO cathode contacts showed enhanced power conversion efficiencies (PCEs), which is independent of the composition of the active layer. More specifically, single-junction OSCs employing PDINO cathode contact with 2 wt.% BCF-additive achieved an average PCE of 17.7%. Based on experimental data and theoretical modeling, we find that the boron cores of BCF coordinate with amino N-oxide terminal substituent of PDINO after generating BCF-H 2 O/methanol complexes. BCF segments with strong electron withdrawing property can effectively reduce the energy levels of PDINO-BCF complex, and thus enhance device PCE when it is used as a cathode contact in OSCs. This strategy can be extended to other types of photovoltaic devices, photodetectors and light emitting diodes.

Zinc acetylacetonate doping for enhanced cathode interface layer in organic solar cells

“…The D18:Y6 OSCs with PDINO + 2%BCF CIL delivered a higher PCE (18.1%) than PDINO devices (17.1%). 25 Metal complexes of acetylacetone are often commercially available with low cost, and exhibit good solubility in solvents. ZrAcac, 15,26 Al(acac) 3 , 27 Hf(Acac) 4 28 and RuAcac 29 have been reported as CILs in OSCs and perovskite solar cells (PSCs).…”

“…The D18:Y6 OSCs with PDINO + 2%BCF CIL delivered a higher PCE (18.1%) than PDINO devices (17.1%). 25…”

Asymmetric Glycolated Substitution for Enhanced Permittivity and Ecocompatibility of High-Performance Photovoltaic Electron Acceptor

“…Thanks to their low weight, intrinsic flexibility, semitransparency and large-area processability, organic solar cells (OSCs) have gained broad interest as a promising photovoltaic technology. − In particular, in the past 5 years, owing to the rapid development of fused-ring electron acceptors (FREAs), the power conversion efficiencies (PCEs) of OSCs have reached 18%. − However, in comparison with conventional inorganic (e.g., silicon, GaAs) solar cells and hybrid perovskite solar cells, the performance of OSCs still greatly lags behind . One of the significant limitations for the further PCE enhancement of OSCs is the relatively low dielectric constant (ε r ) of traditional organic photovoltaic semiconductors (ε r of 3 to 4), which limits the exciton dissociation efficiency .…”

Chiral Polyacetylene with Thermally Activated Delayed Fluorescence Feature for High-Performance Circularly Polarized Light Detection

“…Furthermore, the as-synthesized chiral polymers can be successfully used to detect CPL without an external electrical field at room temperature. To efficiently separate the photoinduced excitons, it is designed to construct a heterojunction for photoresponse improvement. − Specifically, we employed the SP photodetector based on chiral polymers using a photodiode structure with fine-tuning band alignment: ITO/PEDOT: PSS/chiral polymers/C 60 /BCP/Ag, as shown in Figure a. The energy level of the three polymers is measured by cyclic voltammetry (Figure S30 and Table S6).…”