Microscopic Study of Molecular Double Doping

Abstract

Double doping, in which a single dopant molecule induces two charge carriers in an organic semiconductor (OSC), was recently experimentally observed and promises to enhance the efficiency of molecular doping. Here we present a theoretical investigation of p-type molecular double doping in a CN6-CP:bithiophene–thienothiophene OSC system. Our analysis is based on density functional theory (DFT) calculations for the electronic ground state. In a molecular complex with two OSC oligomers and one CN6-CP dopant molecule, we explicitly demonstrate double integer charge transfer and find the formation of two individual polarons on the OSC molecules and a dianion dopant molecule. We show that the vibrational modes and related infrared absorption spectrum of this complex can be traced back to those of the charged dopant and OSC molecules in their isolated forms. The near-infrared optical absorption spectrum calculated by time-dependent DFT shows features of both typical intramolecular polaron excitations and weak intermolecular charge transfer excitations associated with the doping-induced polaron states.

Understanding the Double Doping of Organic Semiconductors Via State Energy Renormalization upon Charging

“…With this description, the most effective dopants generate one free carrier per dopant molecule (doping efficiency η = 100%). However, there are now reports of the double ionization of dopants, − where one dopant molecule generates two charge carriers. These results have two fundamental consequences.…”

Dynamics-induced charge transfer in semiconducting conjugated polymers

“…In the present work we use the range-separated cam-B3LYP functional together with the 6-31g(d) basis set for a sufficient description of the CT transfer character as in our previous work on doping OSCs. 39,40,42,43 van der Waals interaction correction is included by using the Grimme D3 method with Becke-Johnson damping function. 44,45 The DFT calculations are performed by using Gaussian16 46 package.…”

Eliminating the Imbalanced Mobility Bottlenecks via Reshaping Internal Potential Distribution in Organic Photovoltaics

“…[29,30] ))dimalononitrile (Y6) was adopted as the active layer materials (Figure 3a). [31,32] As an important assumption, the cathode p-doping performs better in material combinations with lower hole mobility. In accordance with it, we examined the carrier mobility in PTQ10:Y6 BHJ film at optimum donor:acceptor (D:A) weight ratio of 1:1.2.…”