Untangling Ternary Blends: Connections between film morphology, device performance and reliability in organic electronics
Abstract
Organic electronic device performance and reliability are almost always dependent on the morphology of the active electronic layer.This is particularly true for organic photovoltaic devices (OPVs) whose photoactive bulk heterojunction (BHJ) region consists of a blend of two or more donor and/or acceptor compounds. In particular, OPVs with ternary blend BHJs comprising a donor and two non-fullerene acceptors (NFAs) have achieved efficiencies ~20% by providing greater spectral coverage than binary OPVs. In addition, binaryOPVs have shown extraordinary stabilities of decades if not thousands of years. Methods for achieving desired morphologies is either by solution or vapor phase deposition. The latter is primarily practiced by the enormous global OLED industry. A primary reason for using vacuum-deposited materials is the ease of purifying the source materials to achieve high performance, reliability and reproducibility. To take advantage of the manufacturing infrastructure including very high production speed by roll-to-roll production andknow-how available to OLEDs, OPVs based on vapor-deposited materials must achieve efficiencies comparable to, or exceeding those employing solution-processed materials, although this has not yet been demonstrated. In this project, we propose to determine how to control device properties based on three or more molecular constituents. Specifically, we will use ternary OPVs as the vehicle with which to test our theories, materials, analyses, and methods. Ternary devices are an ideal platform since OPV performance is highly sensitive to morphology, materials purity, and deposition processes. Specifically, we aim to answer the following questions:#Can molecular species (particularly NFAs and donors) be developed that can be deposited in ternary BHJs both from the vapor and solution phases to achieve high efficiency and stable bicontinuous morphologies?#What is the relationship between morphology and device performance; specifically,how do the open circuit voltage (VOC) and charge transfer (CT) properties depend on ternary morphology?#Can the materials and morphologies developed significantly reduce energy losses that currently result in OPVs with power conversion efficiencies less than that of other solar cell technologies?#What are the interactions between the ternary BHJ constituents themselves, or between these constituents and interfaces with charge injection layers, how can they be prevented, and how do these interactions affect device performance and stability?Our efforts are divided into two tasks. Task 1:Understanding the relation of molecular structure and BHJ morphologies of ternary blends on device performance and stability. Task 2:Understanding the effects of ternary blends, their constituents and morphologies on energy loss and open circuit voltage. Success in our efforts is expected to lead to a deeper, quantitative understanding and models of mechanisms governing the properties of multi-component organic electronic active layers. Secondarily, it should significantly accelerate the large-scale production of thin film OPVs and other devices deposited on glass or flexible plastic substrates by leveraging the existing infrastructure for manufacturing OLEDs, leading OPVs to serve as a major source of reliable, environmentally friendly, next generation low cost, thin film solar cell technology. All services, including the Navy, have an increasing need to supply power to its operational units. Thin film OPVs have a lightweight, flexible and durable profile such that they can be easily stowed, transported and deployed in remote and often harsh operating environments. Hence, our research has considerable long-term relevance to the Navy, as well as the other US armed services.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 08, 2024
- Source ID
- N000142412113
Entities
People
- Stephen R. Forrest
Organizations
- Board of Regents of the University of Michigan
- Office of Naval Research
- United States Navy