Accelerated Lifetime Testing of Organic–Inorganic Perovskite Solar Cells Encapsulated by Polyisobutylene

Abstract

Metal halide perovskite solar cells (PSCs) have undergone rapid progress. However, unstable performance caused by sensitivity to environmental moisture and high temperature is a major impediment to commercialization of PSCs. In the present work, a low-temperature, glass-glass encapsulation technique using high performance polyisobutylene (PIB) as the moisture barrier is investigated on planar glass/FTO/TiO/FAPbI/PTAA/gold perovskite solar cells. PIB was applied as either an edge seal or blanket layer. Electrical connections to the encapsulated PSCs were provided by either the FTO or Au layers. Results of a "calcium test" demonstrated that a PIB edge-seal effectively prevents moisture ingress. A shelf life test was performed and the PIB-sealed PSC was stable for at least 200 days. Damp heat and thermal cycling tests, in compliance with IEC61215:2016, were used to evaluate different encapsulation methods. Current-voltage measurements were performed regularly under simulated AM1.5G sunlight to monitor changes in PCE. The best results we have achieved to date maintained the initial efficiency after 540 h of damp heat testing and 200 thermal cycles. To the best of the authors' knowledge, these are among the best damp heat and thermal cycle test results for perovskite solar cells published to date. Given the modest performance of the cells (8% averaged from forward and reverse scans) especially with the more challenging FAPbI perovskite material tested in this work, it is envisaged that better stability results can be further achieved when higher performance perovskite solar cells are encapsulated using the PIB packaging techniques developed in this work. We propose that heat rather than moisture was the main cause of our PSC degradation. Furthermore, we propose that preventing the escape of volatile decomposition products from the perovskite solar cell materials is the key for stability. PIB encapsulation is a very promising packaging solution for perovskite solar cells, given its demonstrated effectiveness, ease of application, low application temperature, and low cost.

Perovskite/Silicon Tandem Solar Cells: Marriage of Convenience or True Love Story? – An Overview

“…However, in the particular case of perovskite/silicon tandem solar cells, the standards already in place in the silicon PV industry have to be adopted to enable market entry and faster acceptance by a highly conservative industry. Reliable encapsulation schemes, e.g., a glass/glass encapsulation using a polymer encapsulant and a butyl rubber or polyisobutylene edge sealant require a thermal stability of at least ≈120–160 °C, depending on the encapsulation material used. A thermal stability in this range will also allow for the use of industrially viable metallization using screen printing of low‐temperature silver pastes.…”

Encapsulation of Printable Mesoscopic Perovskite Solar Cells Enables High Temperature and Long‐Term Outdoor Stability

“…Early in 2016, F. Bella et al has reported an encapsulation/coating method with photocurable fluoropolymers to enhance the stability of PSCs against moisture and even under UV irradiation . Shi et al developed a low‐temperature, glass–glass encapsulation technique using polyisobutylene as the moisture barrier on planar structure PSCs . The polyisobutylene edge‐seal effectively prevented moisture ingress, and improved the stability of devices under damp heat testing and thermal cycling, though the devices still suffered critical degradation during the tests.…”

Surface Electronic Modification of Perovskite Thin Film with Water‐Resistant Electron Delocalized Molecules for Stable and Efficient Photovoltaics

“…On the other hand, we have first demonstrated a surface functionalization method of MAPbI 3 (MA = CH 3 NH 3 + ) film with tetra-alkyl ammonium molecules which could tremendously enhance the humid stability of the perovskite device even under very harsh condition (90% relative humidity). [23][24][25][26] However, it was found that the organic layers with insulated alkyl groups usually limit the carrier extraction and thus result in slight loss of PCEs in our experiments.To protect the perovskite devices with high efficiency, surface-functionalized molecules must combine excellent electrical conductivity and hydrophobic properties. In addition, encapsulation was another effective way to protect perovskites form degradation induced by ambient moisture.…”