Abstract
Perovskite solar cells (PSCs) have shown great potential for next-generation photovoltaics. One of the main barriers to their commercial use is their poor long-term stability under ambient conditions and, in particular, their sensitivity to moisture and oxygen. Therefore, several encapsulation strategies are being developed in an attempt to improve the stability of PSCs in a humid environment. The lack of common testing procedures makes the comparison of encapsulation strategies challenging. In this paper, we optimized and investigated two common encapsulation strategies: lamination-based glass-glass encapsulation for outdoor operation and commercial use (COM) and a simple glue-based encapsulation mostly utilized for laboratory research purposes (LAB). We compare both approaches and evaluate their effectiveness to impede humidity ingress under three different testing conditions: on-shelf storage at 21 °C and 30% relative humidity (RH) (ISOS-D1), damp heat exposure at 85 °C and 85% RH (ISOS-D3), and outdoor operational stability continuously monitoring device performance for 10 months under maximum power point tracking on a roof-top test site in Berlin, Germany (ISOS-O3). LAB encapsulation of perovskite devices consists of glue and a cover glass and can be performed at ambient temperature, in an inert environment without the need for complex equipment. This glue-based encapsulation procedure allowed PSCs to retain more than 93% of their conversion efficiency after 1566 h of storage in ambient atmosphere and, therefore, is sufficient and suitable as an interim encapsulation for cell transport or short-term experiments outside an inert atmosphere. However, this simple encapsulation does not pass the IEC 61215 damp heat test and hence results in a high probability of fast degradation of the cells under outdoor conditions. The COM encapsulation procedure requires the use of a vacuum laminator and the cells to be able to withstand a short period of air exposure and at least 20 min at elevated temperatures (in our case, 150 °C). This encapsulation method enabled the cells to pass the IEC 61215 damp heat test and even to retain over 95% of their initial efficiency after 1566 h in a damp heat chamber. Above all, passing the damp heat test for COM-encapsulated devices translates to devices fully retaining their initial efficiency for the full duration of the outdoor test (>10 months). To the best of the authors' knowledge, this is one of the longest outdoor stability demonstrations for PSCs published to date. We stress that both encapsulation approaches described in this work are useful for the scientific community as they fulfill different purposes: the COM for the realization of prototypes for long-term real-condition validation and, ultimately, commercialization of perovskite solar cells and the LAB procedure to enable testing and carrying out experiments on perovskite solar cells under noninert conditions.
Highlights
Over the past decade, tremendous progress has been made on improving the power conversion efficiency (PCE) of perovskite solar cells (PSCs), which has reached 25.5%.1 With lowcost and up-scalable fabrication methods, this photovoltaic (PV) technology is likely to play a key role in the future of solar energy.[2]
For the glue-based encapsulation technique, which we will refer to below as laboratory research purposes (LAB) encapsulation, a thin glass coverslip was glued on top of the cell with a UV light curing acrylate adhesive (Figure 1b,d)
In the Supporting Information, the optimization of this encapsulation method comparing different UV glues, UV curing durations, and cover glass geometries are described (Figures S1 and S2)
Summary
Tremendous progress has been made on improving the power conversion efficiency (PCE) of perovskite solar cells (PSCs), which has reached 25.5%.1 With lowcost and up-scalable fabrication methods, this photovoltaic (PV) technology is likely to play a key role in the future of solar energy.[2]. A high electrical resistivity is desirable to mitigate potential-induced degradation since it prevents leakage current which could degrade the cell Mechanical properties such as flexibility, a high mechanical strength, adhesion to the contact surfaces within the module, and a thermal expansion coefficient matching that of PSC components are required to withstand long-term outdoor exposure in various climates.[4,7] the maximal thermal budget allowed to avoid damaging the cell during encapsulation depends on the materials used in the perovskite solar cell stack. We compared the effectiveness of these two encapsulation strategies for PSCs by carrying out on-shelf storage, damp heat testing, and outdoor operation
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have