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Nowadays, inorganic CsPbBr 3 perovskite is emerging as a promising candidate as a light-absorbing layer in photovoltaic devices due to its excellent photoelectric property and superior stability under humidity and thermal attacks in comparison with organic cation-based hybrid perovskites. However, the impure perovskite phase and severe interfacial charge recombination have limited the further improvement of device performance. In this work, a vapor-assisted solution technique was introduced to prepare a high-purity CsPbBr 3 film in a perovskite solar cell (PSC). To further reduce the electron−hole recombination and enhance charge extraction, we introduced the novel intermediate energy level of manganese sulfide (MnS) as a hole transport layer in CsPbBr 3 PSC. The as-optimized CsPbBr 3 PSC based on all-inorganic transport layers delivers a power conversion efficiency (PCE) of 10.45% in comparison with 8.16% for the device free of an intermediate layer, which is one of the highest PCEs achieved among the CsPbBr 3 -based PSCs to date. Moreover, the optimized device retained 80% PCE of its initial efficiency over 90 days under 80% relative humidity at 85 °C, indicating an excellent environmental tolerance to boost the commercial application of low-cost, efficient, and stable all-inorganic PSCs.

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Herein, a ternary boron-oxygen-nitrogen embedded polycyclic aromatic hydrocarbon with multiple resonance thermally activated delayed fluorescence (MR-TADF), namely DBNO, is developed by adopting the para boron-πboron and para oxygen-π-oxygen strategy. The designed molecule presents a vivid green emission with a high photoluminescence quantum yield (96 %) and an extremely narrow full width at half maximum (FWHM) of 19 nm/ 0.09 eV, which surpasses all previously reported green TADF emitters to date. In addition, the long molecular structure along the transition dipole moment direction endows it with a high horizontal emitting dipole ratio of 96 %. The organic light-emitting diode (OLED) based on DBNO reveals a narrowband green emission with a peak at 504 nm and a FWHM of 24 nm/0.12 eV. Particularly, a significantly improved device performance is achieved by the TADFsensitization (hyperfluorescence) mechanism, presenting a FWHM of 27 nm and a maximum external quantum efficiency (EQE) of 37.1 %.

The lead-free double perovskite has been proven to be one of the promising alternatives to solve the stability and toxicity problems of lead-based organic−inorganic hybrid perovskite solar cells. Here, highquality Cs 2 AgBiBr 6 double perovskite films with large grains and smooth surface have been prepared through a sequential-vapor-deposition method, and a low-cost and eco-friendly Cu 2 O film with a suitable energy level and good electrical properties was prepared as an efficient hole transport layer by vacuum vapor deposition for the first time. The Cu 2 O-based devices achieve a champion power conversion efficiency increasing from 1.03 to 1.52% and an enhancement of photovoltage from 1.083 to 1.198 V compared with their organic counterparts. More importantly, the Cu 2 Obased devices have excellent stability; they maintained the initial 96% efficiency under environmental conditions after 33 days of unpackaged storage. These results also point out the direction for the further development of these new promising perovskite solar cells.