Reducing hole transporter use and increasing perovskite solar cell stability with dual-role polystyrene microgel particles

Abstract

Perovskite solar cells (PSCs) are a disruptive technology that continues to attract considerable attention due to their remarkable and sustained power conversion efficiency increase. Improving PSC stability and reducing expensive hole transport material (HTM) usage are two aspects that are gaining increased attention. In a new approach, we investigate the ability of insulating polystyrene microgel particles (MGs) to increase PSC stability and replace the majority of the HTM phase. MGs are sub-micrometre crosslinked polymer particles that swell in a good solvent. The MGs were prepared using a scalable emulsion polymerisation method. Mixed HTM/MG dispersions were subsequently spin-coated onto PSCs and formed composite HTM-MG layers. The HTMs employed were poly(triaryl amine) (PTAA), poly(3-hexylthiophene) (P3HT) and Spiro-MeOTAD (Spiro). The MGs formed mechanically robust composite HTMs with PTAA and P3HT. In contrast, Spiro-MG composites contained micro-cracks due the inability of the relatively small Spiro molecules to interdigitate. The efficiencies for the PSCs containing PTAA-MG and P3HT-MG decreased by only ∼20% compared to control PSCs despite PTAA and P3HT being the minority phases. They occupied only ∼35 vol% of the composite HTMs. An unexpected finding from the study was that the MGs dispersed well within the PTAA matrix. This morphology aided strong quenching of the CHNHPbICl fluorescence. In addition, the open circuit voltages for the PSCs prepared using P3HT-MG increased by ∼170 mV compared to control PSCs. To demonstrate their versatility the MGs were also used to encapsulate P3HT-based PSCs. Solar cell stability data for the latter as well as those for PSCs containing composite HTM-MG were both far superior compared to data measured for a control PSC. Since MGs can reduce conjugated polymer use and increase stability they have good potential as dual-role PSC additives.

Perovskite Solar Cells: From the Laboratory to the Assembly Line

“…However, unlike DSSCs, the perovskite absorber tolerates a whole range of HTMs and architectures . Accordingly, a plethora of novel HTMs has been demonstrated in recent years for usage in PSCs.…”

Ambient-air-stable inorganic Cs2SnI6double perovskite thin filmsviaaerosol-assisted chemical vapour deposition

“…By applying this facile, scalable process, lms with high purity and uniformity can be obtained. The growth of lms at a relatively low temperature of 150 C is well adapted to exible device applications, [41][42][43][44][45] when compared to vacuum deposition (190 C). 25 We also demonstrate the importance of addition of hydroiodic (HI) acid to the precursor solution to afford Cs 2 SnI 6 lms with a reduced number of macroscopic defects such as pinholes.…”

P3HT/Phthalocyanine Nanocomposites as Efficient Hole‐Transporting Materials for Perovskite Solar Cells

“…However, for the concentration of phthalocyanine nanowire in P3HT exceeding a 1:1 weight ratio, the film quality decreased and more defects were observed. Hence, P1C1 had the most compact and smooth thin film, which is important to obtain satisfactory electrical contact with a Au electrode . The full surface coverage of various HTMs deposited on perovskite layer were further confirmed by scanning electronic microscopy (SEM) measurement, as shown in Figure S6, Supporting Information.…”