Even though the mesoporous-type perovskite solar cell (PSC) is known for high efficiency, its planar-type counterpart exhibits lower efficiency and hysteretic response. Herein, we report success in suppressing hysteresis and record efficiency for planar-type devices using EDTA-complexed tin oxide (SnO₂) electron-transport layer. The Fermi level of EDTA-complexed SnO₂ is better matched with the conduction band of perovskite, leading to high open-circuit voltage. Its electron mobility is about three times larger than that of the SnO₂. The record power conversion efficiency of planar-type PSCs with EDTA-complexed SnO₂ increases to 21.60% (certified at 21.52% by Newport) with negligible hysteresis. Meanwhile, the low-temperature processed EDTA-complexed SnO₂ enables 18.28% efficiency for a flexible device. Moreover, the unsealed PSCs with EDTA-complexed SnO₂ degrade only by 8% exposed in an ambient atmosphere after 2880 h, and only by 14% after 120 h under irradiation at 100 mW cm⁻².

Final results are reported from operation of the PICO-60 ${\mathrm{C}}_3{\mathrm{F}}_8$ dark matter detector, a bubble chamber filled with 52 kg of ${\mathrm{C}}_3{\mathrm{F}}_8$ located in the SNOLAB underground laboratory. The chamber was operated at thermodynamic thresholds as low as 1.2 keV without loss of stability. A new blind 1404-kg-day exposure at 2.45 keV threshold was acquired with approximately the same expected total background rate as the previous 1167-kg-day exposure at 3.3 keV. This increased exposure is enabled in part by a new optical tracking analysis to better identify events near detector walls, permitting a larger fiducial volume. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at $3.2\times 10^{-41}{\mathrm{cm}}^2$ for a 25 GeV WIMP, improving on previous PICO results for 3–5 GeV WIMPs by an order of magnitude.

New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of ${\mathrm{C}}_3{\mathrm{F}}_8$ located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, $\mathrm{PICO}\text{−}60{\mathrm{C}}_3{\mathrm{F}}_8$ exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than one event per month. A blind analysis of an efficiency-corrected 1167-kg day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the predicted background. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at $3.4\times {10}^{-41}{\mathrm{cm}}^2$ for a $30\text{−}\mathrm{GeV}{\mathrm{c}}^{-2}$ WIMP, more than 1 order of magnitude improvement from previous PICO results.