Suppressing non-radiative loss via a low-cost solvent additive enables high-stable all-polymer solar cells with 16.13% efficiency

摘要

The power conversion efficiency (PCE) of all-polymer solar cells (all-PSCs) has made a huge breakthrough in the past six years, but the PCE is far from the theoretical limit. A key reason for limiting the PCE of all-PSCs is the huge non-radiative loss, limiting open-circuit voltage (V-OC) and fill factor (FF) improvement for all-PSCs. Tuning the chemical structure of the polymer donor and polymer acceptor, and designing suitable interfacial materials are the most common methods to improve the V-OC and FF of all-PSCs, but this method is too costly because synthesizing new materials may be a repeated failure process. In this work, we realized a 16.13% PCE with boosted VOC of 0.86 V and FF of 76.02% for all-PSCs based on PBDB-T (poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithio-phene)) -alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'c:4',5'-c']di-thiophene-4,8 dione)]) and PYF-T via incorporating a low-cost solvent additive 1-chloronaphthalene (CN) into the processing solvent chlorobenzene. A range of device physical analyses indicate that CN additive can effectively suppress the non-radiative loss and energetic disorder in the device. Detailed blend film morphology investigation highlight that CN additive promotes vertical phase separation and pi-pi stacking in PBDB-T:PYF-T blends during film drying processes. These observations exemplify the significance of CN additive as a tool for boosting VOC and FF of all-PSCs, which may initiate an extraordinary field for making solvent additive work in an intelligent way in all-PSCs.

关键词