Organic Photovoltaics with Multiple Donor–Acceptor Pairs

Abstract

Compared with conventional organic solar cells (OSCs) based on single donor–acceptor pairs, terpolymer‐ and ternary‐based OSCs featuring multiple donor–acceptor pairs are promising strategies for enhancing the performance while maintaining an easy and simple synthetic process. Using multiple donor–acceptor pairs in the active layer, the key photovoltaic parameters (i.e., short‐circuit current density, open‐circuit voltage, and fill factor) governing the OSC characteristics can be simultaneously or individually improved by positive changes in light‐harvesting ability, molecular energy levels, and blend morphology. Here, these three major contributions are discussed with the aim of offering in‐depth insights in combined terpolymers and ternary systems. Recent exemplary cases of OSCs with multiple donor–acceptor pairs are summarized and more advanced research and perspectives for further developments in this field are highlighted.

Random terpolymer based on thiophene-thiazolothiazole unit enabling efficient non-fullerene organic solar cells

“…To develop alternative donor polymers, one strategy is to synthesize random terpolymers by incorporating a third component (such as an acceptor unit) to form a Donor-Acceptor1-Donor-Acceptor2 (D-A 1 -D-A 2 )-type polymer [26][27][28][29][30] . For instance, an estersubstituted thiophene unit has been incorporated into PM6 backbone to downshift the molecular energy level and broaden the absorption, leading to simultaneously enhanced short-circuit current density (J sc ) and open-circuit voltage (V oc ) in the device 31 .…”

Stable Covalent Organic Frameworks for Photochemical Applications

“…The charge transfer efficiency dominates the conversion process of photon to chemicals. The methods that are beneficial to charge transfer can promote the whole photochemical conversion efficiency, such as decreasing the pathway of the charge transfer by preparing materials with specific morphologies, design of the layered and ordered structures, regulating the charge transfer route and etc.…”

Recent Advances Toward Highly Efficient Tandem Organic Solar Cells

“…[9] To make the most of the vast existing pool of materials with various bandgaps and overcome the absorption restrictions, ternary blend, and tandem devices were then developed. [9][10][11] By introducing more than one donor (i.e., D1:D2:A structure) and/or acceptor (i.e., D:A1:A2 structure) in a single-junction device, the ternary blend devices strike a good balance between light-harvesting enhancement and device fabrication simplicity. The multiple energy and/or charge transfer pathways will promote the enhanced energy transfer, exciton dissociation and charge collection.…”