The
mesoporous (meso)-TiO2 layer is a key component of high-efficiency
perovskite solar cells (PSCs). Herein, pore size controllable meso-TiO2 layers are prepared using spin coating of commercial TiO2 nanoparticle (NP) paste with added soft polymer templates
(SPT) followed by removal of the SPT at 500 °C. The SPTs consist
of swollen crosslinked polymer colloids (microgels, MGs) or a commercial
linear polymer (denoted as LIN). The MGs and LIN were comprised of
the same polymer, which was poly(N-isopropylacrylamide)
(PNIPAm). Large (L-MG) and small (S-MG) MG SPTs were employed to study
the effect of the template size. The SPT approach enabled pore size
engineering in one deposition step. The SPT/TiO2 nanoparticle
films had pore sizes > 100 nm, whereas the average pore size was
37 nm for the control meso-TiO2 scaffold. The largest pore
sizes were obtained using L-MG. SPT engineering increased the perovskite
grain size in the same order as the SPT sizes: LIN < S-MG <
L-MG and these grain sizes were larger than those obtained using the
control. The power conversion efficiencies (PCEs) of the SPT/TiO2 devices were ∼20% higher than that for the control
meso-TiO2 device and the PCE of the champion S-MG device
was 18.8%. The PCE improvement is due to the increased grain size
and more effective light harvesting of the SPT devices. The increased
grain size was also responsible for the improved stability of the
SPT/TiO2 devices. The SPT method used here is simple, scalable,
and versatile and should also apply to other PSCs.
Semitransparent perovskite solar cells (STPSCs) continue to attract enormous interest because of their potential to provide low-cost renewable energy for building and automotive applications. Whilst many studies have shown that...
Additive engineering has been applied widely to improve the efficiency and/or stability of perovskite solar cells (PSCs). Most additives used to date are difficult to locate within PSCs as they are small molecules or linear polymers. In this work, we introduce, for the first time, carboxylic acid-functionalized nanogels (NGs) as additives for PSCs. NGs are swellable sub-100 nm gel particles. The NGs consist of poly(2-(2-methoxyethoxy) ethyl methacrylate)-co-methacrylic acid-co-ethylenegylcol dimethacrylate (PMEO 2 MA-MAA-EGD) particles prepared by a scalable synthesis, which have a diameter of 40 nm. They are visualized in the perovskite films using SEM and are located at the grain boundaries. X-ray photoelectron and FTIR spectroscopy reveal that the NGs coordinate with Pb 2+ via the −COOH groups. Including the NGs within the PSCs increased the grain size, decreased nonradiative recombination, and increased the power conversion efficiency (PCE) to 20.20%. The NGs also greatly increase perovskite stability to ambient storage, elevated temperature, and humidity. The best system maintained more than 80% of its original PCE after 180 days of storage under ambient conditions. Tensile cross-cut tape adhesion tests are used to assess perovskite film mechanical integrity. The NGs increased both the adhesion of the perovskite to the substrate and the mechanical stability. This study demonstrates that NGs are an attractive alternative to molecularly dispersed additives for providing performance benefits to PSCs. Our study indicates that the NGs act as a passivator, stabilizer, cross-linker, and adhesion promoter.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.