Electric‐Induced Degradation of Cathode Interface Layer in PM7:IT‐4F Polymer Solar Cells

Abstract

Cathode buffer layer interface modification is a commonly used strategy to prepare high‐efficient organic solar cells (OSCs). Nonfullerene OSCs based on PM7:IT‐4F are prepared and modified with poly[(9,9‐bis(3′‐(N,N‐dimethylamino)propyl)‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)] (PFN)‐Br cathode buffer layer. The introduction of the PFN‐Br buffer layer obviously boosts the photovoltaic performance of PM7:IT‐4F‐based OSCs, however, the stability of the PFN‐Br‐modified device shows a serious degradation. By excluding the influence of heat, oxygen, moisture, and light illumination, the degradation is verified to be triggered by the electric effect. As soon as the devices undergo electrical measurement such as applying a bias voltage for the current density–voltage test, the degradation begins. The degradation mechanism of the PFN‐Br‐modified OSCs is investigated in detail with intensity modulated photovoltage spectroscopy/photocurrent spectroscopy (IMPS/IMVS), photoinduced charge extraction linear increasing voltage (Photo‐CELIV), and impendence spectroscopy (IS) technology. The results show that the PFN‐Br cathode buffer layer is deteriorated and increases the interface resistance between active layer and cathode, which hinders charge transport and collection at the electrode, thus weakening the performance of PM7:IT‐4F‐based OSCs. The degradation of PM7:IT‐4F/PFN‐Br OSCs induced by the electric effect proposed herein provides a new inspiration for the degradation study of OSCs.

Additive-assisted strategy for high-efficiency organic solar cells

“…With the expectation of compromising the effect of the two kinds of additives, binary additives have been investigated in the past few years. [124][125][126][127][128][129] For instance, He and Zhao et al reported the OSC based on FTAZ:IDCIC (Fig. 2) with the binary additive, 1-CN&DIO, afforded a decent PCE of 13.58%, much higher than the counterparts with no additive (9.64%), DIO (9.76%), and CN (11.81%), respectively.…”

Powering the Future: A Critical Review of Research Progress in Enhancing Stability of High‐Efficiency Organic Solar Cells

“…As a result, charge transport and extraction are hindered, leading to a degraded device performance. [ 66 ] So far, there needs to be more research on the electrical effect on the stability of high‐efficiency OSCs and its mechanism.…”

An Alcohol‐Soluble N‐Annulated Perylene Diimide Cathode Interlayer for Air‐Processed, Slot‐Die Coated Organic Photovoltaic Devices and Large‐Area Modules

“…Previous studies show that PFN-Br-modified OPVs exhibit photovoltaic performance degradation attributed to an increase in the interface resistance caused by the deterioration of the cathode buffer layer (PFN-Br). [32,33] The deterioration is enhanced by the strong polar group in PFN-Br structure. Because the N-annulated PDI does not have a strong polar group in its structure, this degradation mechanism is minimized with PDIN-EH, which leads to a superior charge transport and charge extraction at the interface between the active layer and electrode.…”