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Self‐assembled monolayers (SAMs) with unique ordered structures and varied anchoring groups have emerged as an excellent interfacial strategy for perovskite solar cells (PSCs). Herein, 3‐carboxypropyl‐triphenyl phosphonium bromide with the participation of the fullerene derivative [6,6]‐phenyl‐C61‐butyric acid (PCBA) as functionalized C‐PCBA SAM, is introduced to stably modify the TiO2/perovskite interface. In the meantime, with strong fullerene cage–iodide interaction, ordered C‐PCBA SAM can passivate interfacial defects and improve the electron transportation. A high efficiency of 24.8% and stabilized power output of 23.9%, are achieved with negligible hysteresis, which is among the best performances for TiO2 planar PSCs. This modified cell also exhibits significantly improved stabilities under different testing conditions; non‐encapsulated devices can maintain 95% of initial efficiency after 1000 h thermal stability testing at 85 °C and 85% after 700 h continuous illumination (≈100 mW cm−2) and maximum‐power‐point tracking. This work provides valuable inspiration for developing highly efficient and stable PSCs by using a convenient SAM reconfiguration strategy. [ABSTRACT FROM AUTHOR]

Low‐dimensional (LD) perovskites can effectively passivate and stabilize 3D perovskites for high‐performance perovskite solar cells (PSCs). Regards CsPbI3‐based PSCs, the influence of high‐temperature annealing on the LD perovskite passivation effect has to be taken into account due to fact the black‐phase CsPbI3 crystallization requires high‐temperature treatment, however, which has been rarely concerned so far. Here, the thermal stability of LD perovskites based on three hydrophobic organic ammonium salts and their passivation effect toward CsPbI3 and the whole device performance, have been investigated. It is found that, phenyltrimethylammonium iodide (PTAI) and its corresponding LD perovskites exhibit excellent thermal stability. Further investigation reveals that PTAI‐based LD perovskites are mainly distributed at grain boundaries, which not only enhances the phase stability of CsPbI3 but also effectively suppresses non‐radiative recombination. As a consequence, the champion PSC device based on CsPbI3 exhibits a record efficiency of 21.0 % with high stability. [ABSTRACT FROM AUTHOR]

Aiming at stable CsPbI3 perovskite solar cells, Ge incorporated for the first time into DMAPbI3‐based precursor systems. Ge incorporation is found to be able to modify crystallization growth of CsPb1−xGexI3 films and reduce annealing temperature and treatment time by lowering CsPbI3 formation energy. The champion power conversion efficiency (PCE) of 19.52% is achieved with a certified PCE of 18.8%, which is the highest performance of CsPbI3 PSCs with alien element‐doping. In addition, in situ formation of GeO2 can passivate the grain boundary and surface defects, thus significantly improving the moisture resistance of the perovskite film and related devices. Excellent operational stability is achieved with no PCE degradation over 3000 h at a fixed bias voltage of 0.85 V under continuous white LED (6500 K) illumination and a nitrogen atmosphere. This work demonstrates that Ge‐incorporation is a promising way to stabilize CsPbI3 perovskite solar cells by simultaneously improving perovskite crystallinity and passivating the grain boundary and interfacial defects. [ABSTRACT FROM AUTHOR]

Besides widely used surface passivation, engineering the film crystallization is an important and more fundamental route to improve the performance of all‐inorganic perovskite solar cells. Herein, we have developed a urea‐ammonium thiocyanate (UAT) molten salt modification strategy to fully release and exploit coordination activities of SCN− to deposit high‐quality CsPbI3 film for efficient and stable all‐inorganic solar cells. The UAT is derived by the hydrogen bond interactions between urea and NH4+ from NH4SCN. With the UAT, the crystal quality of the CsPbI3 film has been significantly improved and a long single‐exponential charge recombination lifetime of over 30 ns has been achieved. With these benefits, the cell efficiency has been promoted to over 20 % (steady‐state efficiency of 19.2 %) with excellent operational stability over 1000 h. These results demonstrate a promising development route of the CsPbI3 related photoelectric devices. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskite cesium lead iodide (CsPbI3) exhibits excellent prospects for commercial application as a light absorber in single‐junction or tandem solar cells due to its outstanding thermal stability and proper bandgap. However, the device performance of CsPbI3‐based perovskite solar cells (PSCs) is still restricted by the unsatisfactory crystal quality and severe non‐radiative recombination. Herein, inorganic additive ammonium halides are introduced into the precursor solution to regulate the nucleation and crystallization of the CsPbI3 film by exploiting the atomic interaction between the ammonium group and the Pb–I framework. The grain boundaries and interfacial contact of the CsPbI3 film have been improved, which leads to significant suppression in the non‐radiative recombination and an enhancement in the charge transport ability. With these benefits, a high efficiency of 18.7% together with an extraordinarily high fill factor of 0.83–0.84 has been achieved, comparable to the highest records reported so far. Moreover, the cell exhibits ultra‐high photoelectrical stability under continuous light illumination and high bias voltage with 96% of its initial power‐conversion efficiency being sustained after 2000 h operation, even superior to the world‐champion CsPbI3 solar cell. The findings are promising for the development and application of all‐inorganic PSCs using a simple inorganic additive strategy. [ABSTRACT FROM AUTHOR]

[Display omitted] Carbon-based perovskite solar cells (C-PSCs) have attracted widespread research interest because of their excellent stability. However, the power conversion efficiency (PCE) of C-PSCs, especially planar C-PSCs, lags far behind the certified efficiency (25.5%) of metal-based PSCs. The simple architecture of planar C-PSCs imparts stringent requirements for device configuration. In this study, we fabricated high-performance planar C-PSCs through device configuration engineering in terms of the perovskite active layer and carbon electrode. Through the combination of component and additive engineering, the crystallization and absorption profiles of perovskite active layer have been improved, which afforded sufficient photogenerated carriers and decreased nonradiative recombination. Furthermore, the mechanical and physical properties of carbon electrode were evaluated comprehensively to regulate the back-interface contact. Based on the compromise of the flexibility and conductivity of carbon film, an excellent back-interface contact has been formed, which promoted fast interface charge transfer, thereby decreasing interface recombination and improving carrier collection efficiency. Finally, the as-prepared devices achieved a remarkable PCE of up to 20.04%, which is a record-high value for planar C-PSCs. Furthermore, the as-prepared devices exhibited excellent long-term stability. After storage for 1000 h at room temperature and 25% relative humidity without encapsulation, the as-prepared device retained 94% of its initial performance. [ABSTRACT FROM AUTHOR]