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Planar-heterojunction perovskite solar cells (PSCs) have experienced rapid evolution in recent years because of the low-temperature processing, suitable alignment, and high mobility of the tin oxide buried contact layer. However, improper SnO2 surface states and poor crystallinity of the top perovskite films are still the main obstacles for the planar PSCs in which performance always lags behind their mesoporous counterparts. Herein, a new buried contact is reported by introducing graphitic carbon nitride (g-C3N4) into the commonly used SnO2 which performs outstanding transmittance, conductivity, and surface states for a high-quality electron-transporting layer. Moreover, the vertical composition and crystallinity of the top perovskite film are manipulated by rich amino groups on the edge of the g-C3N4 nanosheets which induce the prenucleation of the lead-rich species at the buried interface. Benefiting from the high-quality buried contacts and the optimized perovskite layers, the resultant PSCs achieve a champion efficiency of 21.5% with all photovoltaic parameters enhanced in comparison with their control counterparts (

Understanding the fundamental properties of buried interfaces in perovskite photovoltaics is of paramount importance to the enhancement of device efficiency and stability. Nevertheless, accessing buried interfaces poses a sizeable challenge because of their non-exposed feature. Herein, the mystery of the buried interface in full device stacks is deciphered by combining advanced in situ spectroscopy techniques with a facile lift-off strategy. By establishing the microstructure-property relations, the basic losses at the contact interfaces are systematically presented, and it is found that the buried interface losses induced by both the sub-microscale extended imperfections and lead-halide inhomogeneities are major roadblocks toward improvement of device performance. The losses can be considerably mitigated by the use of a passivation-molecule-assisted microstructural reconstruction, which unlocks the full potential for improving device performance. The findings open a new avenue to understanding performance losses and thus the design of new passivation strategies to remove imperfections at the top surfaces and buried interfaces of perovskite photovoltaics, resulting in substantial enhancement in device performance.

As one of the most promising semiconductor oxide materials, titanium dioxide (TiO2) absorbs UV light but not visible light. To address this limitation, the introduction of Ti3+ defects represents a common strategy to render TiO2 visible-light responsive. Unfortunately, current hurdles in Ti3+ generation technologies impeded the widespread application of Ti3+ modified materials. Herein, we demonstrate a simple and mechanistically distinct approach to generating abundant surface-Ti3+ sites without leaving behind oxygen vacancy and sacrificing one-off electron donors. In particular, upon adsorption of organodiboron reagents onto TiO2 nanoparticles, spontaneous electron injection from the diboron-bound O2- site to adjacent Ti4+ site leads to an extremely stable blue surface Ti3+‒O-· complex. Notably, this defect generation protocol is also applicable to other semiconductor oxides including ZnO, SnO2, Nb2O5, and In2O3. Furthermore, the as-prepared photoelectronic device using this strategy affords 103-fold higher visible light response and the fabricated perovskite solar cell shows an enhanced performance.

Metal halide perovskite with high Young's modulus is prone to form cracks when subjected to mechanical stresses such as bending, twisting, or impacting, ultimately leading to a permanent decline in the performance of their photovoltaic devices. These mechanical properties pose challenges to the durability of long‐term service of photovoltaic devices and the production of flexible devices. To address this issue, the poly (lipoic acid‐co‐Styrene) elastomer is employed to modulate the modulus of perovskite films. The peak force quantitative nanomechanical atomic force microscopy measurements and nanoindentation tests demonstrated a reduction in modulus, with the lower modulus preventing the formation of cracks and defects during deformation. Moreover, this approach also suppressed the non‐radiative recombination of perovskite solar cells by leveraging the interaction between functional groups and defects. Through this method, the rigid inverted devices attained a power conversion efficiency of 24.42% alongside remarkable stability. Concurrently, flexible inverted devices achieved a power conversion efficiency of 22.21%. This strategy offers a promising avenue for fabricating flexible perovskite solar cells and enhancing their mechanical durability. [ABSTRACT FROM AUTHOR]

The meticulous control of crystal facets in polycrystalline perovskite films offers valuable insights into the photoelectric properties, varying significantly with different orientations. Exploring effective means to regulate these facets is crucial, and further revealing the underlying mechanisms is needed. Here, the research employed green solution bathing to obtain high‐quality perovskite films with preferred crystallographic orientation. In brief, eco‐friendly 2‐pentanol is used as the solvent, and functional molecules 2‐(dimethylaminomethyl)‐4‐(2‐aminoethylthiomethyl)thiazole (DAT) are introduced into the solution bathing as the solute. By introducing DAT molecules, precise control over perovskite crystal nucleation kinetics is achieved, resulting in films with a preferential (100) facet orientation. Conversely, films without DAT exhibited distinct (111) facet orientation. The regulation of DAT on perovskite film crystal facet is verified through theoretical and crystallographic analyses. Theoretical calculations show that S atom of DAT binds most strongly to the (100) facet of FAPbI3, promoting surface energy reduction and thermodynamic enhancement, favoring (100) crystal orientation. Crystallographic characterization further proved the regulation effect. In addition, PL/TRPL tests confirm the regulation of DAT on superior photoelectric properties of (100)‐oriented perovskite films. The work introduces a novel approach and preparation process for regulating the crystal facets orientation of polycrystalline perovskite films. [ABSTRACT FROM AUTHOR]