High Performance Organic Solar Cells from Conjugated Ribbons.
Abstract
This grant will expand and develop a new and promising class of materials~helical,conjugated ribbons~to have extremely high efficiencies in solar cells. We have created electronacceptors that are mechanically rigid and possess high optical absorbance, particularly in spectralregions complementary to common donors and demonstrated these molecules as ~best in class~materials as the electron transporting material, replacing fullerenes in traditional bulkheterojunction solar cells. They are built from a common perylene dye that through a fewchemical manipulations can be easily made into conjugated ribbons that can accept manyelectrons, a key feature previously reserved for fullerenes. The rod-like molecular structure haslonger persistence length and a much higher optical cross section than that of fullerenes in thevisible region.A two-PI team with a proven track record of success, Colin Nuckolls and Xiaoyang Zhu, willcollaborate to accomplish the three objectives. These objectives will allow us to create highlyefficient materials for solar cells and other optoelectronic devices. Nuckolls will lead the effort todesign, synthesize and test new molecular designs. Zhu will lead the effort in spectroscopy andmicroscopy as tools to understand the properties of the materials created. This team will continueto collaborate with two research scientists at Columbia, Drs. Michael Steigerwald and Fay Ng.Steigerwald has a strong background in materials chemistry and molecular quantum mechanics.Ng is expert in organic chemistry and assists the students and post-doctoral scientists in thepreparative chemistry described below.We have three integrated sets of goals that will allow us to systematically and significantlyimprove the performance of these ribbon structures in solar cells.A. Optimizing oligo-perylene diimide ribbons as electron acceptorsOne of the advantageous features of the oligomers in this proposal is the helical, rather thanplanar, nature of the structure, which retains rigidity but prevents aggregation. We willsystematically change the twist angle of the helical structure to tune the energetics andpersistence length. This will allow us to optimize not only the energetic alignment with donorsbut also optical absorption strength.B. High performance electron acceptors from electron donor-acceptor building blocksTo more broadly tune the electronic properties of the electron accepting ribbons and, moreimportantly, to reduce the exciton binding energy by introducing charge transfer character to theexcited state, we will design new perylenediimide-based ribbons as electron acceptors byincorporating electron-rich and electron-poor segments. These new non-fullerenes acceptors willhave tunable frontier orbitals and low exciton binding energies, while maintaining higherabsorption coefficients and rigidity, as well as connectivity in the solid state for efficient electrontransport. Our preliminary results, described below, indicate that this is a viable strategy.C. A New Design for Electronically and Shape Matched Electron DonorsTo achieve the highest solar cell efficiency, the PIs will design and create donor materialsthat are electronically, structurally, and morphologically matched to the above rigid electronacceptor ribbons. A new design for a matched donor material is put forward to have atransformative effect on organic photovoltaics. This will allow us to not only raise the powerconversion efficiency for these materials by design, but it will also allow us to improve theenvironmental stability of the solar cells.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 03, 2017
- Source ID
- N000141712205
Entities
People
- Colin Nuckolls
Organizations
- Office of Naval Research
- Trustees of Columbia University in the City of New York
- United States Navy