The Crystallinity Control of Polymer Donor Materials for High-Performance Organic Solar Cells

Abstract

Bulk heterojunction (BHJ) organic solar cells (OSCs) can be regarded as one of the most promising energy generation technologies for large-scale applications. Despite their several well-known drawbacks, the devices where polymers are employed as the donor are still leading the OSC universe in terms of performance. Such performance generally depends upon various critical factors such as the crystallinity of the material, the crystallization process during the film formation, and also the final film morphology. Despite a few reviews on the structure of the polymer donor materials and device performance, not enough attention has been paid toward the crystallinity problem. Herein, the structure and crystallinity of the representative polymer donor materials and the corresponding device properties have been briefly reviewed. Furthermore, several typical methods for controlling the crystallinity of materials have been summarized and illustrated as well. Moreover, the obstacles lying in the way of successful commercialization of such polymer solar cells have been systematically discussed. The in-depth interpretation of the crystallinity of the polymer donors in this article may stimulate novel ideas in material design and device fabrication.

A visible to near-infrared nanocrystalline organic photodetector with ultrafast photoresponse

“…GISAXS is a powerful tool to distinguish the arrangements of polymers at the nanoscale. 56 In this study, the characteristic length is around 1.9 nm as the effective q value is in the range of 0.07-1 Å À1 in the out-of-plane (OOP) direction and 0.07-0.8 Å À1 in the in-plane (IP) direction. As can be seen from Fig.…”

Diketopyrrolopyrrole Based Organic Semiconductor Materials for Field-Effect Transistors

“…To fabricate high-performance OFETs, charge transfer mobility (µ), threshold voltage, and current on/off ration are the three key factors. Among these three factors, high charge carrier mobility is the most important and a challenging, since the existing organic semiconductor's charge transfer mobilities are far behind compared to the inorganic Sibased ones, resulting in it not meeting the commercial demand (Qiu et al, 2020). Except the device fabrication technique, the chemical structures of the organic semiconductors play a key role for improvement of the charge carrier's mobility.…”

Triphenyleno[1,2-c:7,8-c′]bis([1,2,5]thiadiazole) as a V-Shaped Electron-Deficient Unit to Construct Wide-Bandgap Amorphous Polymers for Efficient Organic Solar Cells

“…However, the fused building blocks reported so far generally have linear shapes to maintain the crystallinity of the polymers, which is believed to be a prerequisite for highperformance semiconducting polymers. 21,22 There are few building blocks with nonlinear shapes that modulate D−A polymers, which strongly affect the electronic properties and morphologies of the polymers. 23 On the other hand, in bulk heterojunction (BHJ) OSCs, the photoactive layer comprises a nanostructured blend of electron donor and electron acceptor materials, and the performance is a complicated function of interdependent factors, such as the molecular orientation, thin-film crystallinity, miscibility, and energy level alignments of the components.…”

“… , NTz-based polymers exhibit better photovoltaic performance than BTz-based polymers because of the extended molecular plane along with other advantages. However, the fused building blocks reported so far generally have linear shapes to maintain the crystallinity of the polymers, which is believed to be a prerequisite for high-performance semiconducting polymers. , There are few building blocks with nonlinear shapes that modulate D–A polymers, which strongly affect the electronic properties and morphologies of the polymers …”

“…This leads to wide-bandgap polymers, and the low-lying HOMO orbitals are maintained due to the strong electron-withdrawing properties of the BTz segments. The extended π-conjugated plane is expected to induce a face-on orientation of the polymer chains and thus ensure efficient vertical charge transport, , and the unconventional zigzag molecular conformation should strongly affect the solid-state morphology. As a proof of concept, a D–A copolymer PTPTz–IDT was synthesized in combination of the s -indaceno­[1,2- b :5,6- b ′]­dithiophene (IDT) comonomer.…”