Synthesizing Near‐Ultraviolet‐Absorbed Donor for Transparent Polymer Solar Cells. Issue 10 (7th August 2022) - Du, Zurong
Abstract : Wavelength‐selective transparent polymer solar cells (T‐PSCs) have huge developing potential in power‐window applications for their excellent visible transparency and high color‐rendering index. However, the main research interest of devices until now is focused on near‐infrared absorbers for both polymer donor and nonfullerene small‐molecule acceptor (NF‐SMA) due to the lack of appropriate near‐ultraviolet absorbers. Herein, the successful implementation of the T‐PSC devices based on novel kinds of near‐ultraviolet polymer donors combined with a near‐infrared NF‐SMA Y6 is reported. The reported polymer donors are "D1–D2"‐type copolymers employing fluorene and triphenylamine as the two electron‐donating units. The best‐performed one not only shows ultrawide optical bandgap (2.87 eV), leading to high average visible transmittance (AVT) of 96.8% in the thin film, but also has efficient hole mobility (about 5.0 × 10 −6 cm 2 V −1 s −1 ), well‐matched frontier molecular orbital energy levels, and good miscibility with Y6. As a result, the T‐PSC device is obtained with an AVT of 51.4% and PCE of 3.15%, along with favorable light utilization efficiency (LUE) of 1.62% and CRI of 91.6. This is the first example that uses near‐ultraviolet‐absorbed polymer donor to achieve high‐efficiency T‐PSC devices. Abstract : An ultra‐wide bandgap polymer donor (≈2.87 eV) is developed for efficient wavelength‐selective transparent polymer solar cells. The solution‐processed polymer solar cells obtain a power conversion efficiency of >3% along with outstanding average visible transmittance of >50%.