Recently, all-polymer solar cells (all-PSCs) have become an important organic photovoltaic technology, ascribing to their unique characteristics of high stability and mechanical endurance. However, the morphology control between polymer donor and polymer acceptor suffers from tough difficulties, resulting from the nature of rigid planarity and chain entanglement in the conjugated polymer backbones. In this work, we utilize an additive, 1-chloro-naphthalene (CN), to regulate polymer chain stacking and orientation in D18:PY-IT system, resulting in the formation of versatile nano-scale polymer fibrillization between donor and acceptor phases. Consequently, the CN-modified D18:PY-IT blend film shows improved molecular stacking characteristics and distinct nano-scale bi-continuous phase separation. Attributing to the incorporation of CN additive in a bulk-heterojunction (BHJ) D18:PY-IT system, it exhibits higher photovoltaic performance than the as-cast and only thermal annealing (TA) treated devices, where the CN-based device provides a power conversion efficiency (PCE) of 17.31%, an open-circuit voltage (V_OC) of 0.955 V, a short-circuit current density (J_SC) of 24.16 mA·cm⁻², and a fill factor (FF) of 74.99%, respectively. This is one of the highest photovoltaic performances reported in the D18:PY-IT based binary BHJ all-PSCs. Hence, it is evident that the morphology in all-PSCs can be feasibly modulated via incorporating appropriate additive into active layer for achieving excellent photovoltaic performance.

Antimony selenide (Sb₂Se₃) has recently made considerable advancements in photovoltaic, photoelectrochemical, and photodetector research scenarios, owing to its advantageous material merits and superior optoelectronic properties. By contrast, the exploration of flexible Sb₂Se₃ photoelectric devices are less attempted, though it possesses unique one-dimensional (1D) crystal structure to enable large deformation tolerance. Here, we develop a flexible Sb₂Se₃ thin-film photodetector on polyimide substrate. Thanks to the high-quality Sb₂Se₃ light absorber and benign interfaces at both back contact and heterojunction regions, the carrier dynamics are effectively optimized. The leading flexible Sb₂Se₃ photodetector showcases self-powered and broadband features, with exceptional responsivity of 0.51 A·W^–1 and realistic detectivity up to 1.32 × 10¹³ Jones, ultra-fast response speed of 49 ns/351 ns of rise and decay times, and remarkable mechanical deformation stability, flourishing the high-level development for flexible Sb₂Se₃ photodetectors. Interestingly, a tunable single/dual-color flexible imaging system under band alignment modulation, along with a wearable and accurate heart rate/arterial blood oxygen saturation photoplethysmography detection system highlights the great application potential for flexible Sb₂Se₃ photodetectors.

CsPbCl₃ perovskite is considered a highly promising material for ultraviolet (UV) photodetectors due to its exceptional thermal stability and excellent short-wavelength light response. However, its high lattice energy and low polarizability result in extremely low solubility in conventional solvents, making the synthesis of CsPbCl₃ single crystals a significant challenge. In this study, we propose a novel thermodynamically induced crystal restructuring (TICR) process that can transform microcrystalline films (MCFs) into single crystal films (SCFs) within a short period. This method, for the first time, has successfully achieved the synthesis of centimeter-sized CsPbCl₃ SCFs and the mechanism has been explored in depth using in-situ techniques. Furthermore, we report the first instance of a CsPbCl₃ SCF UV photodiode, which exhibits a record-breaking on/off ratio of 3.32 × 10⁷ and a detectivity of up to 1.15 × 10¹⁴ Jones under 0 V bias. It demonstrates excellent response even under weak light conditions of 10 nW·cm⁻² and maintains outstanding stability with almost no performance degradation after 15 months. This study provides a novel approach for the synthesis of perovskite single crystals and holds significant potential for advancing the development of high-performance optoelectronic devices.

Although numerous metal halide perovskite materials have been investigated in the field of optoelectronic, the development of perovskite heterojunctions with exotic structures is still rare. Herein, we report the epitaxial growth of quasi-two-dimensional (Q-2D) perovskites on methylammonium lead iodide (MAPbI₃) single crystals to form perovskite heterojunctions with interfacial bonding. The MAPbI₃ adjacent to epitaxial Q-2D perovskite shows blue shifted photoluminescence with shortened lifetime, which becomes significant with the reduced layer number of the Q-2D perovskites. Our findings suggest the presence of an interfacial strain gradient leading to enhanced photocarrier separation. Accordingly, compared to the MAPbI₃ single crystal detector, the BA₂MAPb₂I₇/MAPbI₃ (BA: n-butylamine) heterojunction-based photodetector demonstrates a bandpass detecting property and exhibits 5 times enhanced external quantum efficiency and 83 times enhanced specific detectivity (D* = 3.26 × 10¹¹ Jones). Remarkably, the unencapsulated BA₂MAPb₂I₇/MAPbI₃ heterojunction is stable in ambient condition for > 300 days. The Q-2D/3D heterojunction shows suppressed ion inter-diffusion due to the presence of Q-2D phase.

Metal halide perovskite solar cell (PSC) has successfully distinguished itself in optoelectronic field by virtue of the sharp rise in power conversion efficiency over the past decade. The remarkable efficiency breakthrough at such a fast speed can be mainly attributed to the comprehensive study on film deposition techniques, especially the effective management of surface and interfacial defects in recent works. Herein, we summarized the current trends in performance enhancement for PSCs, with a focus on the generally applicable strategies in high-performance works, involving deposition methods, compositional engineering, additive engineering, crystallization manipulation, charge transport material selection, interfacial passivation, optical coupling effect and constructing tandem solar cells. Promising directions and perspectives are also provided.

Bandgap-graded materials present varying spectral responses at different positions, making them possible to be used as an alternative to photoactive materials array in multi-spectral responsive devices, thus miniaturizing the apparatus. However, the preparation of bandgap-graded materials usually requires complicated deposition process. Here we report a facile low-temperature solution process to make films with lateral bandgap gradients, which form spontaneously via self-spreading and interdiffusion of solutions. We show lead halide perovskite films with MAPbCl₃-MAPbBr₃ and MAPbBr₃-MAPbI₃ gradients, which exhibit light absorption onsets ranging from 410 to 781 nm. The bandgap-graded films were used to make self-powered multiband photodetectors, which show different spectral responses at different positions without applying bias voltage. Furthermore, self-powered spectrometers were made by using the multiband photodetectors.

In this research highlight, recent significant advances with hot-assisted blade-coating or air knife-assisted blade-coating of different perovskite compositions with bandgaps ranging from 1.3 eV to 1.9 eV (i.e. wide-bandgap or small-bandgap perovskites with mixed cations and anions, 2D/3D perovskites, Pb/Sn binary perovskites, and all-inorganic perovskites) for single-junction or tandem PSCs are discussed, with an emphasis on elucidating the distinct ink formulation engineering strategies, crystal growth mechanisms, crystallization kinetics, and optoelectronic properties of the different perovskite compositions.