TY - JOUR

T1 - Traps and transport resistance are the next frontiers for stable non-fullerene acceptor solar cells

AU - Wöpke, Christopher

AU - Göhler, Clemens

AU - Saladina, Maria

AU - Du, Xiaoyan

AU - Nian, Li

AU - Greve, Christopher

AU - Zhu, Chenhui

AU - Yallum, Kaila M.

AU - Hofstetter, Yvonne J.

AU - Becker-Koch, David

AU - Li, Ning

AU - Heumüller, Thomas

AU - Milekhin, Ilya

AU - Zahn, Dietrich R.T.

AU - Brabec, Christoph J.

AU - Banerji, Natalie

AU - Vaynzof, Yana

AU - Herzig, Eva M.

AU - MacKenzie, Roderick C.I.

AU - Deibel, Carsten

N1 - Publisher Copyright: © 2022, The Author(s).

PY - 2022/12

Y1 - 2022/12

N2 - Stability is one of the most important challenges facing material research for organic solar cells (OSC) on their path to further commercialization. In the high-performance material system PM6:Y6 studied here, we investigate degradation mechanisms of inverted photovoltaic devices. We have identified two distinct degradation pathways: one requires the presence of both illumination and oxygen and features a short-circuit current reduction, the other one is induced thermally and marked by severe losses of open-circuit voltage and fill factor. We focus our investigation on the thermally accelerated degradation. Our findings show that bulk material properties and interfaces remain remarkably stable, however, aging-induced defect state formation in the active layer remains the primary cause of thermal degradation. The increased trap density leads to higher non-radiative recombination, which limits the open-circuit voltage and lowers the charge carrier mobility in the photoactive layer. Furthermore, we find the trap-induced transport resistance to be the major reason for the drop in fill factor. Our results suggest that device lifetimes could be significantly increased by marginally suppressing trap formation, leading to a bright future for OSC.

AB - Stability is one of the most important challenges facing material research for organic solar cells (OSC) on their path to further commercialization. In the high-performance material system PM6:Y6 studied here, we investigate degradation mechanisms of inverted photovoltaic devices. We have identified two distinct degradation pathways: one requires the presence of both illumination and oxygen and features a short-circuit current reduction, the other one is induced thermally and marked by severe losses of open-circuit voltage and fill factor. We focus our investigation on the thermally accelerated degradation. Our findings show that bulk material properties and interfaces remain remarkably stable, however, aging-induced defect state formation in the active layer remains the primary cause of thermal degradation. The increased trap density leads to higher non-radiative recombination, which limits the open-circuit voltage and lowers the charge carrier mobility in the photoactive layer. Furthermore, we find the trap-induced transport resistance to be the major reason for the drop in fill factor. Our results suggest that device lifetimes could be significantly increased by marginally suppressing trap formation, leading to a bright future for OSC.

UR - http://www.scopus.com/inward/record.url?scp=85133126421&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/6aca3a68-f5b3-3784-8073-27055848e803/

U2 - 10.1038/s41467-022-31326-z

DO - 10.1038/s41467-022-31326-z

M3 - Article

C2 - 35778394

VL - 13

JO - Nature Communications

JF - Nature Communications

SN - 2041-1723

IS - 1

M1 - 3786

ER -