New publication "Energy Transfer to a Stable Donor Suppresses Degradation in Organic Solar Cells"

New publication "Energy Transfer to a Stable Donor Suppresses Degradation in Organic Solar Cells" by Andreas Weu, Rhea Kumar, Julian F. Butscher, Vincent Lami, Fabian Paulus, Artem A. Bakulin, and Yana Yaynzof in the Advanced Functional Materials.

Abstract:

 
Despite many advances toward improving the stability of organic photovoltaic devices, environmental degradation under ambient conditions remains a challenging obstacle for future application. Particularly conventional systems employing fullerene derivatives are prone to oxidize under illumination, limiting their applicability. Here, the environmental stability of the small molecule donor DRCN5T together with the fullerene acceptor PC70BM is reported. It is found that this system exhibits exceptional device stability, mainly due to almost constant short‐circuit current. By employing ultrafast femtosecond transient absorption spectroscopy, this remarkable stability is attributed to two separate mechanisms: 1) DRCN5T exhibits high intrinsic resistance toward external factors, showing no signs of deterioration. 2) The highly sensitive PC70BM is stabilized against degradation by the presence of DRCN5T through ultrafast, long‐range energy transfer to the donor, rapidly quenching the fullerene excited states which are otherwise precursors for chemical oxidation. It is proposed that this photoprotective mechanism be utilized to improve the device stability of other systems, including nonfullerene acceptors and ternary blends.
 
 
For the paper as PDF click here.
 
 

New paper " Insights from Device Modeling of Perovskite Solar Cells"

New paper "Insights from Device Modeling of Perovskite Solar Cells" by N. Tessler and Y. Vaynzof in ACS. Energy Lett. 4 (5), 1260 (2020).

Abstract:

In this Perspective, we explore the insights into the device physics of perovskite solar cells gained from modeling and simulation of these devices. We discuss a range of factors that influence the modeling of perovskite solar cells, including the role of ions, dielectric constant, density of states, and spatial distribution of recombination losses. By focusing on the effect of nonideal energetic alignment in perovskite photovoltaic devices, we demonstrate a unique feature in low-recombination perovskite materials: the formation of an interfacial, primarily electronic, self-induced dipole that results in a significant increase in the built-in potential and device open-circuit voltage. Finally, we discuss the future directions of device modeling in the field of perovskite photovoltaics, describing some of the outstanding open questions in which device simulations can serve as a particularly powerful tool for future advances in the field.

The full paper here: https://pubs.acs.org/doi/abs/10.1021/acsenergylett.0c00172