Search

At present, one of the major factors limiting the further improvement of inverted (p‐i‐n) perovskite solar cells (PSCs) is trap‐assisted non‐radiative recombination at the perovskite/electron transporting layer (ETL) interface. Surface passivation with organic ammonium salt is a powerful strategy to improve the performance of PSCs. Herein, an effective method by using propylamine hydroiodide (PAI) and 1,3‐diaminopropane dihydroiodide (PDADI) is reported to modify the perovskite/ETL interface. These two ammonium salts do not form new perovskite but directly passivate the defects on the perovskite surface after annealing. The results show that the PDADI‐modified perovskite films possess a lower surface defect density and less non‐radiative recombination as well as improved charge carrier transport. Based on this strategy, the PDADI‐modified p‐i‐n PSCs deliver an impressive efficiency of 25.09% (certified 24.58%) with an open‐circuit voltage of 1.184 V. Furthermore, the unencapsulated PDADI‐modified PSCs also exhibit good storage stability, retaining 91% of initial PCE at 65 °C in a N2 glove box for 1300 h. This strategy provides an efficient route to fabricate highly efficient and stable inverted p‐i‐n structured PSCs. [ABSTRACT FROM AUTHOR]

Elpasolite Cs2AgBiBr6 also known as double perovskite has been touted in recent years as a promising alternative to the lead‐based perovskite for light harvesting. Its structure and properties mainly stem from the replacement of Pb2+ cation with a pair of aliovalent silver (Ag+) and bismuth (Bi3+) cations. Although the elpasolite Cs2AgBiBr6 exhibits improved stability, its photophysical properties and device performance are inferior to those of the Pb‐based perovskites. To date, numerous efforts have been geared toward the development of efficient Cs2AgBiBr6 solar cells. However, the indirect, wide bandgap and high exciton binding energy of Cs2AgBiBr6 have limited such efforts. This has been attributed to its low (zero) electronic dimensionality (0D), formation of small polaronic states, and interfacial imperfections with charge transporting layers. In this review, the different aspects of the elpasolite Cs2AgBiBr6 in relation to compositional and interlayer interactions in solar cell are discussed, and its suitability for photovoltaic application is assessed, accompanied by potential measures to further advance its performance. An alternate application of Cs2AgBiBr6 in photocatalysis, which takes advantage of its less toxicity and better stability, is also discussed. [ABSTRACT FROM AUTHOR]

Inorganic cesium lead halide perovskites offer a pathway towards thermally stable photovoltaics. However, moisture‐induced phase degradation restricts the application of hole transport layers (HTLs) with hygroscopic dopants. Dopant‐free HTLs fail to realize efficient photovoltaics due to severe electrical loss. Herein, we developed an electrical loss management strategy by manipulating poly(3‐hexylthiophene) with a small molecule, i.e., SMe‐TATPyr. The developed P3HT/SMe‐TATPyr HTL shows a three‐time increase of carrier mobility owing to breaking the long‐range ordering of "edge‐on" P3HT and inducing the formation of "face‐on" clusters, over 50 % decrease of the perovskite surface defect density, and a reduced voltage loss at the perovskite/HTL interface because of favorable energy level alignment. The CsPbI2Br perovskite solar cell demonstrates a record‐high efficiency of 16.93 % for dopant‐free HTL, and superior moisture and thermal stability by maintaining 96 % efficiency at low‐humidity condition (10–25 % R. H.) for 1500 hours and over 95 % efficiency after annealing at 85 °C for 1000 hours. [ABSTRACT FROM AUTHOR]

A new small molecular hole-transporting material, 1,3,6,8-tetrakis[N-(p-methoxyphenyl)-N′-(9,9′-dimethyl-9H-fluoren-2-yl)-amino]pyrene (TFAP) was synthesized and applied in CH3NH3PbI3-perovskite solar cells. A best power conversion efficiency of 19.7% with a photovoltage of 1.11 V has been achieved. [ABSTRACT FROM AUTHOR]

Abstract: A readily available small molecular hole‐transporting material (HTM), OMe‐TATPyr, was synthesized and tested in perovskite solar cells (PSCs). OMe‐TATPyr is a two‐dimensional π‐conjugated molecule with a pyrene core and four phenyl‐thiophene bridged triarylamine groups. It can be readily synthesized in gram scale with a low lab cost of around US$ 50 g−1. The incorporation of the phenyl‐thiophene units in OMe‐TATPyr are beneficial for not only carrier transportation through improved charge delocalization and intermolecular stacking, but also potential trap passivation via Pb–S interaction as supported by depth‐profiling XPS, photoluminescence, and electrochemical impedance analysis. As a result, an impressive best power conversion efficiency (PCE) of up to 20.6 % and an average PCE of 20.0 % with good stability has been achieved for mixed‐cation PSCs with OMe‐TATPyr with an area of 0.09 cm2. A device with an area of 1.08 cm2 based on OMe‐TATPyr demonstrates a PCE of 17.3 %. [ABSTRACT FROM AUTHOR]

Abstract: A readily available small molecular hole‐transporting material (HTM), OMe‐TATPyr, was synthesized and tested in perovskite solar cells (PSCs). OMe‐TATPyr is a two‐dimensional π‐conjugated molecule with a pyrene core and four phenyl‐thiophene bridged triarylamine groups. It can be readily synthesized in gram scale with a low lab cost of around US$ 50 g−1. The incorporation of the phenyl‐thiophene units in OMe‐TATPyr are beneficial for not only carrier transportation through improved charge delocalization and intermolecular stacking, but also potential trap passivation via Pb–S interaction as supported by depth‐profiling XPS, photoluminescence, and electrochemical impedance analysis. As a result, an impressive best power conversion efficiency (PCE) of up to 20.6 % and an average PCE of 20.0 % with good stability has been achieved for mixed‐cation PSCs with OMe‐TATPyr with an area of 0.09 cm2. A device with an area of 1.08 cm2 based on OMe‐TATPyr demonstrates a PCE of 17.3 %. [ABSTRACT FROM AUTHOR]

Two new hole transporting materials (HTMs) based on triphenylamine and carbazole core moieties are designed and applied in planar perovskite solar cells. 18.2% power conversion efficiency (PCE) has been achieved, and 84% of the initial performance can be retained after 50 days. [ABSTRACT FROM AUTHOR]

A novel multi-functional interface material (TAAPyr) is first developed as a defect passivation layer and a protect layer against moisture for PSCs application. Consequently, the efficiency of TAAPyr-based device can increase form 20.37% to 22.45%, with an unencapsulated device retaining 90% of its initial efficiency after storage for 600h at ∼65% humidity. [Display omitted] • A hydrophobic multi-functional interface material is developed for PSCs application. • TAAPyr-treated PSCs shows an improvement in efficiency from 20.37% to 22.45%. • Device long-term stability has greatly been enhanced. Surface treatment of perovskite films with interface materials is an effective strategy to resolve trap-mediated nonradiative recombination toward high efficiency and stability of perovskite solar cells (PSCs). However, interface materials for multi-functional treatment have been rarely investigated in PSCs. In this work, a novel pyrene-based organic material (TAAPyr) is first introduced as a defect passivation layer and a protect layer against moisture for PSCs application. With the TAAPyr interfacial modification, both perovskite surface defects and nonradiative recombination are effectively decreased as well as the carrier transport in device is also enhanced, As a consequence, the best power conversion efficiencies (PCE) up to 22.45% for TAAPyr-based device was obtained, clearly outperforming the control one (20.37%). Moreover, it was found that the π-conjugated TAAPyr can promote intermolecular face-to-face stacking on the surface perovskite film, which is favorable to making the perovskite surface more hydrophobic and consequently enhance PSCs long-term stability. The un-encapsulated PSCs can retain 92% of the initial PCE after storage for 600 h at ∼65% RH, in comparison with 64% efficiency retention of the device without TAAPyr under the same conditions. This work presents a new strategy to enhance the efficiency and stability of PSCs by multi-functional π–conjugated passivator. [ABSTRACT FROM AUTHOR]