Poly(vinylidene fluoride‐co‐hexafluoropropylene) additive in perovskite for stable performance of carbon‐based perovskite solar cells

Abstract

The efficiency of perovskite devices is depending on the crystallization process with a controlled microstructure. Perovskite precursors with polymer additive significantly improve the perovskite film crystallinity, large grain boundaries, serve as passivating defect sites yielding increased power conversion efficiency (PCE). In this study, we improved the hole-transport free carbon-based perovskite solar cells by using polymer additive to passivate the perovskite grains with large size crystal and assist to grow with the preferred orientation of the polycrystalline perovskite layer. The polymer additive systematically alters the morphology of the perovskite films. The perovskite with polymer additives exhibited reduced trap density, which could enhance the open-circuit voltage.The fluoro-polymer as an additive into perovskite layer facilitated a hydrogen bond with organic cation to form H-F bond, which could prevent degradation from moisture. The solar device with 5 wt% PVDF-HFP additives achieved $14% improvement in open-circuit voltage and yielded a PCE of 11.11%. Moreover, the shelf-life of the solar device retains 86% from its original efficiency with a period of 30 days (stored under ambient condition, 60%-70% humidity). It is revealing that the fluoro-polymer enhances the passivation of perovskite grains and gives a hope in perovskite photovoltaics.

The effect of permanent electric dipoles on the stability and photoelectric properties of MAPbI3 films

“…These suggest that a suitable amount of P(VDF–TrFE) enhances the crystalline quality and suppresses the non-radiative recombination of perovskite films. 28–30 In contrast, with the further increase of the concentration to 5 mg mL −1 , the intensities of absorption and PL peak decrease, because P(VDF–TrFE) is the ferroelectric material with a large bandgap (4–5 eV) that cannot absorb the light with the wavelengths below 310 nm, 31,32 and a large amount of it would inevitably reduce the volume fraction of MAPbI 3 .…”

Fabrication strategies for high quality halide perovskite films in solar cells

“…Narendhiran et al reported a method of using PVDF-HFP as an additive. 87 The high electronegative fluorine atoms in PVDF-HFP could combine with hydrogen atoms of the MA cation and form hydrogen bonds, which could reduce the nucleation rate during the crystallization process of the perovskite. In this way, the perovskite films showed enlarged grain sizes and improved crystallinity.…”

Recent Advances in Quality Strengthening of Perovskite Films by Additive Engineering for Efficient Solar Cells

“…This significantly enhances the crystallinity and film quality by effectively retarding the process of perovskite crystal formation and aggregation during the initial nucleation stage. At the same time, due to the presence of the F---H bond, [87] Copyright 2021, Wiley-VCH. B,C) Reproduced with permission.…”

“…C) Environmental stability of PVDF-HFP-modified PSC devices. A) Adapted with permission [87]. Copyright 2021, Wiley-VCH.…”