Unraveling the Charge‐Carrier Dynamics from the Femtosecond to the Microsecond Time Scale in Double‐Cable Polymer‐Based Single‐Component Organic Solar Cells

Abstract

color management, and easy manufacturing on a large scale-all being hallmarks of promising low environmental-impact photovoltaic technologies. [1,2] A record efficiency of around 19% has been recently achieved for bulk-heterojunction (BHJ) OSCs based on a nonfullerene electron acceptor. [3] Processing kinetically mixed electron donor (D) and acceptor (A) into thin-film BHJ composites typically results in nonequilibrium microstructures, which are generally thermodynamically unstable. As a consequence, unfavorable microstructure phase separation and/or diffusion of donor/acceptor components may evolve upon external stress such as temperature or illumination, resulting in microstructurerelated performance losses. [4][5][6][7][8][9] As an alternative, organic photovoltaic (OPV) materials based on covalently linked electron donors and acceptors have been developed for almost two decades, but only recently made a major step toward more competitive performance. Nevertheless, the basic processes in single-component organic solar cells (SCOSCs), like efficient light absorption, exciton dissociation, and charge transport, directly mimic those in conventionally blended BHJ composites. [10] Single-component organic solar cells (SCOSCs) have witnessed great improvement during the last few years with the champion efficiency jumping from the previous 2-3% to currently 6-11% for the representative material classes. However, the photophysics in many of these materials has not been sufficiently investigated, lacking essential information regarding charge-carrier dynamics as a function of microstructure, which is highly demanded for a better understanding and potential guidance for further improvements. In this work, for the first time, the charge-carrier dynamics of a representative doublecable polymer, which achieves efficiencies of over 6% as an active layer in SCOSCs, is investigated across seven orders of magnitude in time scale, from fs-ps charge generation to ns-µs charge recombination processes. Specific emphasis is placed on understanding the impact of thermal post-treatment on the charge dissociation and recombination dynamics. Annealing the photoactive layer at 230 °C results in the highest photovoltaic performance because of efficient charge generation in parallel to suppressed recombination. This work intends to present a complete picture of the charge-carrier dynamics in SCOSCs using the representative double-cable polymer PBDBPBICl.

A Two‐in‐One Annealing Enables Dopant Free Block Copolymer Based Organic Solar Cells with over 16% Efficiency

“…Though single‐component organic solar cells (OSCs) are with good mechanical and operational stability, compared to traditional donor‐acceptor bulk‐heterojunction (BHJ) OSCs, their best power conversion efficiency (PCE) is lagged far behind (10% vs. 19%), seriously limiting the prospect. [ 1‐15 ] Recently, block copolymer based OSCs have drawn great attention from the field for breaking the efficiency bottleneck. [ 16‐20 ] Even the claim of single‐ component for this kind of systems is still challenged, block copolymer based OSCs still realize some progress in pursuing photovoltaic performance.…”

Double Asymmetric Core Optimizes Crystal Packing to Enable Selenophene‐based Acceptor with Over 18 % Efficiency in Binary Organic Solar Cells

“…Organic solar cells (OSCs), with significant progress, have been regarded as one of the promising technologies for clean energy owing to their intrinsic advantages of solution processability, semitransparency, and flexibility [1–9] . Recently, the swift growth of power conversion efficiencies (PCEs) of OSCs has been achieved, mainly resulting from the emergence of novel A‐D‐A structural non‐fullerene acceptors (NFAs) and donor polymers [10–35] .…”

N-Annulated Perylene Bisimide-Based Double-Cable Polymers with Open-Circuit Voltage Approaching 1.20 V in Single-Component Organic Solar Cells

“…Both electron-donating and electron-withdrawing materials prefer to establish self-aggregation, destroying the optimum microphase separation and causing low efficiency of charge generation and PCEs in OSCs. 15,16 Covalently linking contributors of electrons and acceptors of electrons into one conjugated material to reduce self-aggregated ability is an efficient way to increase device stability, 17,18 which is also known as "single-component organic solar cells" (SCOSCs).…”

“…Power conversion efficiencies (PCEs) for single-junction OSCs have surpassed 19% due to the rapid progress of nonfullerene acceptors in recent years. , Such exciting outcomes set the tone for the utilization of OSCs in flexible and large-area devices. − However, due to heat and light stress, binary OSCs suffer from being unstable challenges during long-term operation. Both electron-donating and electron-withdrawing materials prefer to establish self-aggregation, destroying the optimum microphase separation and causing low efficiency of charge generation and PCEs in OSCs. , Covalently linking contributors of electrons and acceptors of electrons into one conjugated material to reduce self-aggregated ability is an efficient way to increase device stability, , which is also known as “single-component organic solar cells” (SCOSCs).…”