Design of UV-Absorbing Donor Molecules for Nearly Imperceptible Organic Solar Cells
Melissa L. Ball, Quinn Burlingame, Hannah L. Smith, Tianran Liu, Sean Parkin, Antoine Kahn, Yueh‐Lin Loo
Abstract
Transparent photovoltaic cells are an emerging technology that can provide point-of-use electricity generation for building-integrated applications. While most transparent solar cells to date target absorption of the photon-rich near-infrared portion of the solar spectrum, these devices compromise color neutrality and transparency because of parasitic absorption of long-wavelength visible light. One solution to eliminate parasitic absorption is to employ materials that absorb near-ultraviolet light with sharper absorption cutoffs. Herein, we demonstrate organic donor materials based on N,N′-diaryl-diamines that incorporate a series of aryl linkers to systematically tune their absorption profiles. When paired with acceptor 4,6-bis(3,5-di-4-pyridinylphenyl)-2-methylpyrimidine in an inverted architecture with an indium tin oxide top electrode and an organic optical outcoupling layer, the three best-performing transparent solar cells exhibit average photopic-response-weighted transmittances of 80.3–82.0% and color-rendering indices of 95.0–97.1, both of which are records for organic photovoltaics, with power-conversion efficiencies of 0.43–0.70%.