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Antimony selenosulfide (Sb2(S,Se)3) has been emerging as a promising light absorber owing to its tunable bandgap (1.1–1.7 eV), high absorption coefficient (>105 cm−1), and excellent phase and environmental stability. Lithium salt‐doped 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxy‐phenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) has been generally used as the hole transport layer (HTL) in these high‐efficiency antimony selenosulfide solar cells so far. However, the lithium‐ion reactions and migration in this HTL may cause serious challenges for the stability of these solar cells. Herein, stable and low‐cost tin monosulfide (SnS) nanoparticles surface‐modified nickel oxide (NiOx) as an inorganic hole transport layer to fabricate highly efficient and stable all‐inorganic solar cells is developed. It is found that NiOx films not only demonstrate a higher conductivity but also form better energy band alignment after SnS surface treatment. Consequently, the power conversion efficiency of the full inorganic Sb2(S,Se)3 solar cells increases from 4.85% to 6.41%. Most importantly, the devices also demonstrate much improved thermal, moisture, and long‐term stabilities as compared to the solar cells with spiro‐OMeTAD hole transport layer. [ABSTRACT FROM AUTHOR]

Wide‐bandgap (WBG) perovskite solar cells (PSCs) have garnered significant attention for their potential applications in tandem solar cells. However, their large open‐circuit voltage (VOC) deficit and serious photo‐induced halide segregation remain the main challenges that impede their applications. Herein, a post‐treatment strategy without thermal annealing is presented to form a 2D top layer of 2‐thiopheneethylammonium lead halide (n = 1) on WBG perovskites. This thermal annealing‐free post‐treatment method can more effectively passivate the defects of WBG methylamine (MA)‐free formamidinium/cesium lead iodide/bromide perovskite films and suppress photo‐induced perovskite phase segregation, as compared with the thermal annealing method that yields multi‐2D phases. The resulting opaque and semi‐transparent 1.66 eV‐bandgap perovskite solar cells deliver maximum power conversion efficiencies of 21.47% (a small VOC deficit of 0.43 V) and 19.11%, respectively, both of which are among the highest reports for inverted MA‐free WBG PSCs. Consequently, four‐terminal all‐perovskite tandem cells realize a remarkable efficiency of 26.64%, showing great promise for their applications in efficient multi‐junction tandem solar cells. [ABSTRACT FROM AUTHOR]

Antimony selenosulfide (Sb2(S,Se)3) has been emerging as a promising light absorber in the past few years owing to tunable bandgap (1.1–1.7 eV), high absorption coefficient (>105 cm−1) and excellent phase and environmental stability. However, the efficiency of Sb2(S,Se)3 solar cells lags far behind the Shockley–Queisser limit. One of the critical obstacles originates from various extrinsic and intrinsic defects. They mostly locate in the deep energy levels and are prone to form recombination centers, inhibiting the improvement of device performance. Herein, surface post‐treatment via potassium iodide is introduced to fabricate high‐quality Sb2(S,Se)3 films and solar cells. The surface post‐treatment not only manipulates the crystal growth process to form compact films with larger grain size but also forms better band alignment and inhibits the formation of deep‐level defects antimony antisite (SbSe), thus improving the quality of heterojunction. Consequently, the resultant Sb2(S,Se)3 solar cells achieve a champion power conversion efficiency of 9.22%. This study provides a new strategy of passivating deep‐level intrinsic defects via surface post‐treatment for high‐efficiency Sb2(S,Se)3 solar cells. [ABSTRACT FROM AUTHOR]

External encapsulation technique as a straightforward craft process has been adopted to prevent the infiltration of moisture and oxygen, thereby improving environmental stabilities of lead halide perovskite solar cells (PSCs). However, irreversible light‐induced degradation originating from various vacancies and ion diffusion or migration inside the device cannot be efficiently solved by external encapsulation. Herein, an internal encapsulation strategy by introducing NbCl5 at the buried tin oxide/perovskite interface and spin‐casting n‐butylammonium bromide on top of perovskite is developed to comprehensively passivate the vacancies and hence block the channels for ion diffusion or migration. The internal encapsulation strategy results in better homogeneous electron transport layer and effective vacancy passivation at the buried interface and simultaneously generates a more homogeneous, better crystallized perovskite in the vertical direction with significantly reduced residual PbI2. Furthermore, fewer oxygen vacancies and formation of ultrathin Nb2O5 lead to a better interfacial energy level alignment for electron transfer. As a result, power conversion efficiency (PCE) of the resulting PSCs is as high as 24.01%. More importantly, the device demonstrates an excellent stability, retaining 88% of its initial PCE at its maximum power point tracking measurement (under 100 mW cm–2 white light illumination at ≈55 °C temperature, in N2 atmosphere) after 1000 h. [ABSTRACT FROM AUTHOR]

Trap‐induced nonradiative recombination and decomposition are the major limiting factors that hinder the development of mixed‐halide wide‐bandgap perovskite solar cells. Specifically, the incorporation of formamidinium (FA+) and bromide in wide‐bandgap (WBG) perovskite materials leads to shallow‐energy‐level traps and inferior light stability. Herein, the electron‐withdrawing molecule 2,3,5,6 tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) is used as an effective passivator and stabilizer, which has molecular interaction with the FA+ cation for reducing trap densities and enhancing the stability of WBG perovskite solar cells. It is found that the extended π aromatic system in F4‐TCNQ can enhance the binding energy and stabilize the FA+ cation in perovskite films. Furthermore, the 1.67 eV bandgap inverted perovskite solar cells with a small amount of F4‐TCNQ have shallower defect levels, reduced trap density, and decreased nonradiative recombination, therefore giving a remarkably improved power conversion efficiency (PCE) of 20.0%. Most importantly, the unencapsulated devices with F4‐TCNQ additive have greatly enhanced stability, maintaining 88% of their peak PCEs under continuous illumination after 840 h, whereas the control devices only retain 48% of their PCEs after 500 h. [ABSTRACT FROM AUTHOR]