The hole transport layer (HTL)-free carbon-based perovskite solar cells (C-PSCs) are promising for commercialization owing to their excellent operational stability and simple fabrication process. However, the power conversion efficiencies (PCE) of C-PSCs are inferior to the metal electrode-based devices due to their open-circuit voltage (V _oc) loss. Herein, time-resolved confocal photoluminescence microscopy reveals that grain boundary defects at the perovskite/carbon interface are very likely to function as nonradiative recombination centers in HTL-free C-PSCs. A versatile additive Li₂CO₃ is used to modify the conformal tin oxide electron transport layer for HTL-free C-PSCs. Li₂CO₃ modification can result in enhanced charge extraction and optimized energy alignment at electron transport layer/perovskite interface, as well as suppressed defects at perovskite top surface due to Li₂CO₃-induced formation of PbI₂ crystallites. Such dual interfacial passivation ultimately leads to significantly improved V _oc up to 1.142 V, which is comparable to the metal electrode-based devices with HTL. Moreover, a record-high PCE of 33.2% is achieved for Li₂CO₃-modified C-PSCs under weak light illumination conditions, demonstrating excellent indoor photovoltaic performance. This work provides a practical approach to fabricate low-cost, highly efficient carbon-based perovskite solar cells.

Antimony-based halide perovskites have attracted significant attention owing to their unique optoelectronic properties and low toxicity. However, the distinct defect physics and high exciton binding energy of antimony-based perovskites compared with their lead-based analogues significantly hinder the photovoltaic performance of antimony-based perovskite solar cells (PSCs). In this work, a feasible strategy by regulating the precursor composition is introduced to mitigate the defects and impurity phases of Cs₃Sb₂Cl_xI_9−x films. An optimized content of excess SbI₃ in the precursor composition was found to effectively suppress the CsI impurity phases in the obtained Cs₃Sb₂Cl_xI_9−x films, leading to enhanced crystallinity and reduced defects. Furthermore, the obtained Cs₃Sb₂Cl_xI_9−x films exhibited an increased dielectric response and reduced exciton binding energy, which are conducive to exciton dissociation and carrier transport. A champion efficiency of 3.42% was achieved with the optimized solar cell devices, which is one of the highest efficiencies reported for all-inorganic antimony-based PSCs. These findings provide new perspectives for exploring high-efficiency antimony-based PSCs.

We fabricate HTL-free carbon electrode perovskite solar cells with polypyrrole in carbon paste, achieving a PCE of 18.48% under AM 1.5G and 26.74% at 2000 lux, along with a peak detectivity of 1.96 × 10 ¹³ Jones in photodetector mode.

Benefiting from the booming development of self-assembled monolayer (SAM) based hole-transporting materials, inverted perovskite solar cells (PSCs) have attained a certified power conversion efficiency (PCE) beyond 27.0%, exhibiting great potential for commercialization. However, conventional SAM molecules are prone to self-aggregation owing to their inherent molecular configurations, which readily induced defective and inhomogeneous deposition. In addition, state-of-the-art SAM-based hole-transporting layers are generally deposited in inert environments, while the ambient moisture is expected to further deteriorate the homogeneity of the SAM layers. In this work, a mixed-solvent system of ethanol/N,N-dimethylformamide (DMF) was adopted for the deposition of Me-4PACz SAMs in ambient conditions, which enables significant suppression of intermolecular aggregation in precursor solution and moisture-induced inhomogeneity. The high-quality homogeneous SAM-based hole-transporting layers, along with subsequently optimized perovskite buried interface properties, further empower a prominent increase in the PCE of inverted PSC devices up to 25.0%.

Effective passivation of bulk and interface defects is one of the key drivers for achieving highly efficient and stable p-i-n perovskite solar cells (PSCs). Despite the versatility of bulky ammonium cations in defect passivation, ionic migration of these cations under light and thermal stresses is undesirable for maintaining the integrity of the passivation layer and thus detrimental to the device performance and long-term stability. To address this issue, a stepwise passivation approach employing 2-methoxyphenylethylammonium (2-MeO-PEA⁺) cation and piperazine dihydroiodide (PipDI) is proposed. By integrating bulk incorporation and subsequent surface treatment, the passivation approach synergistically mitigates both bulk and interface defects, and thereby enhances the resilience of the perovskite layer against light and thermal stresses. Owing to the significantly improved morphology, crystallinity, and optoelectronic properties of the perovskite layer, a champion PSC device with a PCE of 26.10% and outstanding stability is achieved, demonstrating the feasibility of the proposed two-step passivation approach.

Perovskite (ABX₃) nanocrystals have garnered significant attention as interfacial passivation materials for perovskite solar cells (PSCs) due to their tunable optoelectronic properties. However, single-component systems often suffer from insufficient defect passivation and poor film stability, limiting their practical application. To address these challenges, we develop a MnBr₂ doping strategy for CsPbBr₃ nanocrystals, which enables precise control over their morphology and phase evolution via B-site Pb²⁺/X-site Br⁻ stoichiometric regulation. Systematic doping induces a progressive morphological transition from cubic to quasi-spherical geometries, accompanied by a phase transformation from cubic CsPbBr₃ to hexagonal Cs₄PbBr₆. The optimized mixed-phase nanocrystals exhibit synergistic effects in interfacial defect passivation and charge transport enhancement, leading to PSCs modified with CsPbBr₃/Cs₄PbBr₆ heterostructures achieving a champion power conversion efficiency (PCE) of 23.33% along with enhanced stability. This work not only elucidates the fundamental structure–property relationships governing MnBr₂-doped nanocrystal evolution but also establishes a new materials design paradigm for high-performance PSC interfaces.