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physica status solidi (a), 2015

Scientific Reports, 2016

In CH3NH3PbI3-based high efficiency perovskite solar cells (PSCs), tiny amount of PbI2 impurity was often found with the perovskite crystal. However, for two-step solution process-based perovskite films, most of findings have been based on the films having different morphologies between with and without PbI2. This was mainly due to the inferior morphology of pure perovskite film without PbI2, inevitably produced when the remaining PbI2 forced to be converted to perovskite, so advantages of pure perovskite photoactive layer without PbI2 impurity have been overlooked. In this work, we designed a printing-based two-step process, which could not only generate pure perovskite crystal without PbI2, but also provide uniform and full surface coverage perovskite film, of which nanoscale morphology was comparable to that prepared by conventional two-step solution process having residual PbI2. Our results showed that, in two-step solution process-based PSC, pure perovskite had better photon ab...

In CH 3 NH 3 PbI 3-based high efficiency perovskite solar cells (PSCs), tiny amount of PbI 2 impurity was often found with the perovskite crystal. However, for two-step solution process-based perovskite films, most of findings have been based on the films having different morphologies between with and without PbI 2. This was mainly due to the inferior morphology of pure perovskite film without PbI 2 , inevitably produced when the remaining PbI 2 forced to be converted to perovskite, so advantages of pure perovskite photoactive layer without PbI 2 impurity have been overlooked. In this work, we designed a printing-based two-step process, which could not only generate pure perovskite crystal without PbI 2 , but also provide uniform and full surface coverage perovskite film, of which nanoscale morphology was comparable to that prepared by conventional two-step solution process having residual PbI 2. Our results showed that, in two-step solution process-based PSC, pure perovskite had better photon absorption and longer carrier lifetime, leading to superior photocurrent generation with higher power conversion efficiency. Furthermore, this process was further applicable to prepare mixed phase pure perovskite crystal without PbI 2 impurity, and we showed that the additional merits such as extended absorption to longer wavelength, increased carrier lifetime and reduced carrier recombination could be secured. Recently, organometal trihalide perovskite materials having composition ABX 3 (e.g. A = Cs + , CH 3 NH 3 + (meth-ylammonium, MA), or HC(NH 2) 2 + (formamidinium, FA); B = Pb or Sn; X = I, Br or Cl) have been investigated extensively for use as light-absorbing material in solar cells because of their unique properties such as direct optical bandgap, broadband light absorption, bipolar transport, and long carrier diffusion length. Since the first report about perovskite solar cells (PSC) having 3.81% power conversion efficiency (PCE) by Kojima et al. in ref. 1, which triggered intensive research in the development of PSC, remarkable enhancement in power conversion efficiency (PCE) reaching 20% has been achieved during past several years 2–4. In conventional silicon-based p-n junction photovoltaic (PV) devices, the pure crystal structure in photoac-tive layer has been known to be advantageous to efficient charge transport and reduced exciton quenching for high efficiency solar cell. However, in MAPbI 3-based PSC showing high efficiency, tiny amount of residual PbI 2 impurity was often found with the perovskite crystal phase, even though the equimolar composition of organic (MAI) and inorganic (PbI 2) components was utilized to fully convert them to perovskite crystal 3,5–14. Therefore, various approaches have been reported to find out if perovskite crystal with PbI 2 impurity would be advantageous to the performance of PSC or not. However, in general, the crystalline structure and nanoscale morphology of perovskite photoactive layers are significantly influenced by their deposition methodology 15–22 , and therefore those reports should be individually interpreted depending on their growth mechanism. Chen el al. reported an approach to produce pure MAPbI 3 film by treating as-deposited PbI 2 film with MAI vapor for several hours, from which PbI 2 component could be reversibly regenerated when annealed at 150 °C 5,6. They showed that the regenerated PbI 2 from the pure MAPbI 3 crystal structure by annealing was helpful to pas-sivate grain boundary (GB) between crystal domains, consequently improving their device performances due to the reduced recombination 6. Similarly, Zhang et al. investigated the role of PbI 2 in their perovskite film, grown by spin-casting hydrohalide deficient PbI 2 ·xHI (x = 0.9~1) precursor under MA vapor atmosphere. Using their

J. Mater. Chem. A, 2015

Advanced materials (Deerfield Beach, Fla.), 2015

Planar CH3 NH3 PbI3 perovskite solar cells with constant 17.2% average power conversion efficiency irrespective of the scan rate are described. These properties are attributed to the formation of pure CH3 NH3 PbI3 thin film by introduction of HI solution. Thereby charge injection/separation efficiency, charge collection efficiency, diffusion coefficient, carrier's life time, and traps are improved.

Organic Electronics, 2015

IPTEK Journal of Proceedings Series, 2017

Journal of Technical Education Science, 2021

In this study, the Perovskite material CH3NH3PbI3 was prepared using two-step sequential solution deposition technique. The treatment condition for Perovskite film including dipping duration, reaction temperature and annealing temperature was studied. Crystal structure, grain size, and purity of the prepared material were examined using XRD and SEM methods. The results indicate that controlling treatment condition has a significant effect on the crystallinity and purity of Perovskite film. Under suitable condition, the obtained Perovskite material has a tetragonal structure and grain size ranges from 200 to 400 nm. The Perovskite film was then applied as a light-harvesting material in Perovskite solar cell. The device exhibits a power conversion efficiency of 5.18% with JSC of 13.6 mA cm-2, VOC of 0.83 V, and fill factor of 45.9%.

Latvian Journal of Physics and Technical Sciences, 2017

Organometal halide perovskites are promising materials for lowcost, high-efficiency solar cells. The method of perovskite layer deposition and the interfacial layers play an important role in determining the efficiency of perovskite solar cells (PSCs). In the paper, we demonstrate inverted planar perovskite solar cells where perovskite layers are deposited by two-step modified interdiffusion and one-step methods. We also demonstrate how PSC parameters change by doping of charge transport layers (CTL). We used dimethylsupoxide (DMSO) as dopant for the hole transport layer (PEDOT:PSS) but for the electron transport layer [6,6]-phenyl C61 butyric acid methyl ester (PCBM)) we used N,N-dimethyl-N-octadecyl(3-aminopropyl)trimethoxysilyl chloride (DMOAP). The highest main PSC parameters (PCE, EQE, VOC ) were obtained for cells prepared by the one-step method with fast crystallization and doped CTLs but higher fill factor (FF) and shunt resistance (Rsh ) values were obtained for cells prepa...