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Rare earth ion-doped inorganic photochromic (PC) materials have recently garnered increasing research interest due to their excellent reversibility, fatigue resistance, and diverse PC performances. Apatite-type materials, in particular, have emerged as a focal point, offering the potential for exchanging multiple cations and anions with stronger tolerance. In comparison to other inorganic PC materials, apatite-type PC materials exhibit more abundant color changes and absorption bands and centers, creating new and substantial opportunities for adjusting and optimizing PC properties, deepening the understanding of PC mechanisms, and enabling construction of novel PC materials and development of multifunctional applications. This review comprehensively summarizes and discusses recent progress in apatite-type PC materials. It covers various aspects, including the PC properties of reported apatite-type PC materials, the pivotal role of traps in PC reactions, the energy transfer mechanism between luminescent centers and color centers, the prediction of PC properties through first-principles calculations, and the systematic regulation of color changes and absorption bands and centers during PC reactions. Benefiting from multiple color variations and extensive absorption band regulation, apatite configuration PC materials exhibit broad prospects and significant potential for various frontier applications, such as optical modulation, photo-switching, anti-counterfeiting, erasable optical information storage, and temperature sensing. Subsequently, this review outlines some challenges and prospects in the research and design of apatite-type PC materials, aiming to guide the exploration of structural design of new inorganic PC materials, further regulating and controlling the PC effect and expanding practical application domains. [ABSTRACT FROM AUTHOR]

P‐type semiconductor cuprous oxide (Cu2O) offers promising optoelectronic applications such as solar cells and photodetectors owing to its considerable absorption coefficients and high carrier mobility. However, polycrystalline Cu2O films with low carrier mobility resulting from excessive grain boundaries and structure disorder fail to meet the demands for these optoelectronic applications. Here a stress‐assisted thermal oxidation method to fabricate p‐type <110>‐textured quasi‐single crystalline Cu2O (c‐Cu2O) wafers with centimeter‐scale grains is developed. It is found that strain energy induced by thermal contact stress plays a critical role in crystal growth. The resultant <110>‐textured quasi‐single c‐Cu2O wafers exhibit excellent crystallinity with rocking curve having a low full width at half maximum of 0.022°, a low defect density of 2 × 1011 cm−3, a high mobility exceeding 100 cm2 V−1 s−1, and a long minority lifetime of 98.5 µs. Such quasi‐single c‐Cu2O wafers lead to efficient solar cells with an open‐circuit voltage of 0.95 V and highly responsive photodetectors with superior cycling stability. These results indicate not only the advancement of fabricating high‐quality Cu2O wafers upon controllable methodology but also the promising optoelectronic applications using p‐type metal oxide semiconductors. [ABSTRACT FROM AUTHOR]

SnO2 compact layer (c‐SnO2) frequently suffers from degradation in high temperature processes (HTP) such as crack, worse interfacial contact, and electrical properties, that is, annealing effect. To solve this problem, a kind of bifunctional SnO2 colloid is developed by using small molecular oxalate whose organic components can be removed clearly at a low temperature process (LTP). The c‐SnO2 and SnO2 mesoporous layer (m‐SnO2) derived from the fresh and aged sols with the same colloid show no annealing effect, decreasing oxygen vacancy, and adsorbing water on increasing annealing temperature. The champion devices of LTP and HTP SnO2 planar perovskite solar cells (PSCs) achieve, respectively, stabilized photoelectric conversion efficiencies (PCEs) of 20.74% and 20.70%. In contrast, the performance of champion devices of their mesoporous counterparts is significantly improved, showing nearly hysteresis free character with stabilized PCEs of 22.40% and 22.37%, respectively. The inclusion of m‐SnO2 plays a role of an energy bridge, improving electrons collection efficiency, which is supported by photoluminescence and transient photoluminescence characterizations. HTP SnO2 mesoporous PSCs can preserve 97.6% and 80% of their initial PCEs after aging for 25 weeks and 8‐h irradiated/16‐h dark cycle within 104 h. The high stability of HTP SnO2 PSCs may ascribe to low oxygen vacancy and adsorbed water of HTP SnO2. [ABSTRACT FROM AUTHOR]

Core–shell nanomaterials have led to their fascinating properties in optical applications due to the localized surface plasmon resonance (LSPR). Herein, a mesoporous core–shell Au@Cu2−xS nanomaterial with dual LSPR characteristics is introduced to stabilize and passivate the perovskite/spiro‐OMeTAD interface of perovskite solar cells (PSCs). Thanks to the LSPR, Au@Cu2−xS nanoparticles (NPs) have the potential to enhance the infrared absorption and intensify the local electric field at the perovskite/spiro‐OMeTAD interface. The embedding of the mesoporous Au@Cu2−xS in the spiro‐OMeTAD layer can improve the contact and form "bridges" between perovskite grains and spiro‐OMeTAD. With the help of cationic surfactant cetyltrimethylammonium bromide, these mesoporous Au@Cu2−xS NPs can passivate surface traps and smooth the valence‐band offset at the perovskite/spiro‐OMeTAD interface for hole transferring. Furthermore, the improved hole mobility can offer balanced charge transport and prevent the carrier accumulation at interfaces. As a result, the Au@Cu2−xS(20:10)‐based PSCs achieves a champion efficiency over 22%, higher than that of the Au@Cu2−xS‐based device. [ABSTRACT FROM AUTHOR]

Nickel oxide (NiOx) is desirable hole selective material (HSMs) for perovskite photovoltaics because of the characteristic in stability and low cost. However, they deliver limited open‐circuit voltage (VOC) compared to some organic HSMs. As it is known, the performance of perovskite solar cells is predominantly limited by trap‐assisted non‐radiative recombination at the perovskite/hole‐selective layer interfaces. A typical lithium‐doping strategy leads to the valence‐band maximum shift and the electronic levels of NiOx can be tuned robustly to match perovskite active layer in perovskite solar cells. More critically, carrier dynamics studies demonstrate another critical PN4N interlayer strategy reduced interfacial density of defect sites and trap‐assisted recombination. These merits contribute coordinately to lower energy loss across the perovskite/NiOx interface and facilitate charge transport process through the relevant interface, yielding VOC values increase to 1.14 V and power conversion efficiencies over 20%. [ABSTRACT FROM AUTHOR]