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Photothermal agents (PTAs) with minimized side effects are critical for transforming cancer photothermal therapy (PTT) into clinical applications. However, most currently available PTAs lack true selective activation to reduce side effects because of heavy spectral overlap between photothermal agents and their corresponding products. This study reports the construction of activatable PTAs with target-initiated large spectral separation for highly effective reduction of side effects. Such designed probes involve two H

ZnO as a promising electron transport layer (ETL) to TiO2 for perovskite solar cells (PSCs) has achieved a power conversion efficiency (PCE) of 18.9%; however, this is still lower than that obtained for TiO2-based PSCs (higher than 20%). Herein, we report the fabrication of high-efficiency methylammonium (MA) and Cs co-alloyed formamidinium (FA) triple cation perovskite based ZnO PSCs via delicate control of the cation compositions and annealing temperatures. By virtue of structural, morphological, spectral and electrochemical characterizations and analysis, we found that the incorporation of MA and Cs into FA perovskite enables the formation of a highly crystalline black phase perovskite with reduced surface roughness, which inhibits charge recombination and promotes electron transfer at the ZnO/perovskite/spiro-OMeTAD interfaces and hence improves Jsc and FF values of the cell. As a result, the ZnO PSC based on MA0.1FA0.75Cs0.15PbI3 annealed at 110 °C achieved a PCE as high as 20.09%, exceeding the previous highest efficiency recorded for ZnO ETL based PSCs. The optimized MA0.1FA0.75Cs0.15PbI3 material demonstrated excellent reproducibility and long-term cell durability under ambient conditions within 1000 h. Particularly, the incorporation of a small amount of Br into the triple cation perovskite, i.e., MA0.1FA0.75Cs0.15PbI2.9Br0.1 led to a further enhancement in PCE of up to 20.44%, which is comparable with the best-performing MA and Cs-containing FA-based lead halide TiO2 PSCs.

Fabricating a 1D electron transport layer (ETL) with bifunctionalities capable of effectively extracting electrons from a fully covering perovskite layer and synergistically blocking charge recombination between electrons in the cathode and holes in the perovskite is of great importance for high performance perovskite solar cells (PSCs). Herein, we report a compact and even ZnO:I nanopillar planar ETL that enables the deposition of a fully covering and highly uniform perovskite layer by a facile one-step spin-coating method. We find that the crystal growth of 1D ZnO along the [0001] direction of a hexagonal single crystal is largely suppressed owing to iodine doping, which leads to a low-aspect-ratio and dense 1D nanopillar aligned architecture, and thus promotes one-step deposition of the perovskite layer. As characterized by optical spectroscopy, Kelvin probe force microscopy, and electrochemical assays, the resultant ZnO:I nanopillar ETL film exhibits high optical transparency, a reduced work function and superior electron extraction ability. As a result, the optical–electrical conversion efficiency is promoted to as high as 18.24%, exceeding the previous highest efficiency recorded for 1D ETL based CH3NH3PbI3 PSCs. The enhanced performance is discussed in detail based on a well-matched work function between ZnO:I and the perovskite, fast electron extraction from the perovskite into the ZnO:I ETL, and improved electron transport rate and retarded charge recombination at the 1D ZnO:I ETL/perovskite interface. This work provides a novel and efficient 1D ETL via alien element doping and crystal oriented growth control for maximizing PSC performance.