Potassium-doped organometal halide perovskite solar cells (PSCs) of more than 20% power conversion efficiency (PCE) without I-V hysteresis were constructed. The crystal lattice of the organometal halide perovskite was expanded with increasing of the potassium ratio, where both absorption and photoluminescence spectra shifted to the longer wavelength, suggesting that the optical band gap decreased. In the case of the perovskite with the 5% K+, the conduction band minimum (CBM) became similar to the CBM level of the TiO2-Li. In this situation, the electron transfer barrier at the interface between TiO2-Li and the perovskite was minimised. In fact, the transient current rise at the maximum power voltages of PSCs with 5% K+ was faster than that without K+. It is concluded that stagnation-less carrier transportation could minimise the I-V hysteresis of PSCs.

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We demonstrate a highly efficient hybrid crystalline silicon (c-Si) based photovoltaic devices with hole-transporting transparent conductive poly-(3,4-ethlenedioxythiophene):poly(styrenesufonic acid) (PEDOT:PSS) films, incorporating a Zonyl fluorosurfactant as an additive, compared to non additive devices. The usage of a 0.1% Zonly treated PEDOT:PSS improved the adhesion of precursor solution on hydrophobic c-Si wafer without any oxidation process. The average power conversion efficiency η value was 10.8%-11.3%, which was superior to those of non-treated devices. Consequently, c-Si/Zonyl-treated PEDOT:PSS heterojunction devices exhibited the highest η of 11.34%. The Zonyl-treated soluble PEDOT:PSS composite is promising as a hole-transporting transparent conducting layer for c-Si/organic photovoltaic applications.

We have developed quantitative and spatially resolved imaging techniques to identify the origin of nonradiative-radiative recombination and carrier transport losses in perovskite solar cells, offering potential for future real-time tracking of the lab-scaled devices and fast assessment of screening the large-area modules. By dual-chloride passivation strategy, the resulting 25.49 cm 2 perovskite solar module achieves a certified power conversion efficiency of 17.88%.

Interface engineering is imperative to boost the extraction capability in perovskite solar cells (PSCs). We propose a promising approach to enhance the electron mobility and charge transfer ability of tin oxide (SnO2) electron transport layer (ETL) by introducing a two-dimensional carbide (MXene) with strong interface interaction. The MXene-modified SnO2 ETL also offers a preferable growth platform for perovskite films with reduced trap density. Through a spatially resolved imaging technique, profoundly reduced non-radiative recombination and charge transport losses in PSCs based on MXene-modified SnO2 are also observed. As a result, the PSC achieves an enhanced efficiency of 20.65% with ultralow saturated current density and negligible hysteresis. We provide an in-depth mechanistic understanding of MXene interface engineering, offering an alternative approach to obtain efficient PSCs.