Highly efficient planar perovskite solar cells through band alignment engineering

Solvent engineering approach via introducing poly (3, 4-ethylene dioxy-thiophene)–poly (styrene sulfonate) (PEDOT:PSS) into photosensitive absorber layer for ambient temperature processed efficient inverted planar perovskite solar cells

Vacuum thermal-evaporated SnO2 as uniform electron transport layer and novel management of perovskite intermediates for efficient and stable planar perovskite solar cells

Ligand-exchange TiO2 nanocrystals induced formation of high-quality electron transporting layers at low temperature for efficient planar perovskite solar cells

Achieving efficient inverted planar perovskite solar cells with nondoped PTAA as a hole transport layer

The facile synthesis and beneficial properties of tin oxide have driven the development of efficient planar perovskite solar cells (PSCs). To increase the PSC performance, alkali salts are used to treat the SnO2 surface to minimize the defect states. However, the underlying mechanism of alkali cations' role in the PSCs needs further exploration. Herein the effect of alkali fluoride salts (KF, RbF, and CsF) on the properties of SnO2 and PSC performance is investigated. The results show different alkali have significant roles depending on their nature. Larger cations Cs+ preferably locate at the SnO2 film surface to passivate surface defects and enhance conductivity, while smaller cations like Rb+ or K+ cations tend to diffuse into the perovskite layer to reduce trap density of the material. The former effect leads to enhanced fill factor while the latter effect increases the open circuit voltage of the device. It is then demonstrated that a dual cation post-treatment of the SnO2 layer with RbF and CsF achieves PSC with a significantly higher power conversion efficiency (PCE) of 21.66% compared to pristine PSC with a PCE of 19.71%. This highlights the significance of defect engineering of SnO2 using selective multiple alkali treatment to improve PSC performance.

High efficiency and negligible hysteresis planar perovskite solar cells based on NiO nanocrystals modified TiO2 electron transport layers

Colloidal synthesis of Y-doped SnO2 nanocrystals for efficient and slight hysteresis planar perovskite solar cells

Interface engineering with NiO nanocrystals for highly efficient and stable planar perovskite solar cells

Synergistic effect of caprolactam as lewis base and interface engineering for efficient and stable planar perovskite solar cells

RF sputtered CdS films as independent or buffered electron transport layer for efficient planar perovskite solar cell

Low temperature processed ternary oxide as an electron transport layer for efficient and stable perovskite solar cells

Efficient planar perovskite solar cells based on low-cost spin-coated ultrathin Nb2O5 films

Defining low-temperature engineering protocols for efficient planar perovskite solar cell (PSC) preparation is important for fabrication simplification and low-cost production. In the present work, we have defined a low-temperature (123 °C) protocol for the preparation from a solution of SnO2 layers which are efficient for an application as an electron transporting layer (ETL) in PSCs. Thin, conformal, and transparent layers have been obtained. The related PSCs have shown best devices with a power conversion efficiency of 18.22% and low-hysteresis J- V curves (a hysteresis index of 6.7%). Charge injection has been thoroughly studied by photoluminescence decay measurements. The decay curves followed a biexponential function. The injection of holes into the spiro-OMeTAD layer was found very fast and is a no-limiting step. On the other side, the charge injection into the oxide ETLs depends on its structure and on the oxide. The time constant for the low-temperature SnO2 layers is close to that of the mesoporous benchmark layers with a fast (surface) and a slow (bulk) component at 11 and 129 ns with relative contributions calculated at 13% and 87%, respectively. The phenomena occurring at a longer time scale have been investigated by impedance spectroscopy. The SnO2 cell spectra showed no intermediate-frequency inductive loop. The very low frequency part of the spectra was characterized by the beginning of an arc of a circle at the origin of a very large resistance over a large applied potential range. This resistance, along with an intermediate-frequency resistance, has been assigned to a recombination resistance and explains the very large Voc achievable with SnO2 PSCs. The existence of a capacitance at the intermediate frequency with a noticeable low value at about 0.2 mF·cm-2 is linked with the low hysteresis of the devices.

High performance planar perovskite solar cells based on CH3NH3PbI3-x(SCN)x perovskite film and SnO2 electron transport layer prepared in ambient air with 70% humility

Among the factors that lead to the reduction of the efficiency of perovskite solar cells (PSCs) the difficulty involved in realizing a high-quality film and the efficient charge transfer that takes place at the interface between electron-transport layer (ETL) and perovskite is worth mentioning. Here, a strategy for planar-type devices by natural bio-functional interfaces that uses a buried electron-transport layer made of cobalamin complexed tin oxide (SnO2 @B12 ) is demonstrated. Having systematically investigated the effects of SnO2 @B12 interfacial layer in perovskite solar cells, it can be concluded that cobalamin can chemically link the SnO2 layer and the perovskite layer, resulting in improved perovskite film quality and interfacial defect passivation. Utilizing SnO2 @B12 improves the efficiency of planar-type PSCs by 20.60 %. Furthermore, after 250 h of exposure to an ambient atmosphere, unsealed PSCs containing SnO2 @B12 degrade by 10 %. This research provides a viable method for developing bio-functional molecules that will increase the effectiveness and durability of planar-perovskite solar cells.