Chemical structure and processing solvent of cathode interlayer materials affect organic solar cells performance

This academic paper investigates the impact of chemical structure and processing solvents on the performance and stability of cathode interlayer (CIL) materials in organic solar cells (OSCs). The research compares a newly synthesised CIL, F-PDIN-EH, processed with polar (methanol), amphiphilic (1-butanol), and non-polar (heptane) solvents, against the widely used PDINO processed in methanol. The study finds that while F-PDIN-EH-based devices offer comparable efficiency to PDINO, they exhibit consistently lower stability, especially when processed with heptane. This degradation is primarily attributed to increased surface recombination and imbalanced charge mobility, providing crucial insights for developing more sustainable OSC technologies.

How Litos Lite supported this work

Litos Lite was used for several characterisation measurements of the organic solar cells (OSCs) and electron-only devices.

Specifically, the Litos-Lite setup was employed for:

•Stability measurements of the OSCs2. These were conducted according to established ISOS protocols:

◦ ISOS-D-1 for shelf stability (in the dark, open circuit, at room temperature).

◦ ISOS-L-1 for photostability (under 1 sun illumination, open circuit, at room temperature).

◦ ISOS-T-1 for thermal stability (in the dark, open circuit, at 85 °C).

• Light intensity-dependent Jsc and Voc measurements of the OSCs.

• Dark J-V measurements of the electron-only devices. These devices were measured in the dark while being stored under different environmental conditions.

The Litos-Lite setup was equipped with a Wavelabs Sinus LS2 solar simulator with an AM 1.5 spectrum for these measurements.