Novel nanostructured electron transport compact layer for efficient and large-area perovskite solar cells using acidic treatment of titanium layer.

A new method for the deposition of a pinhole-free compact layer of TiO2 is introduced for the development of efficient perovskite solar cells. Acidic treatment of titanium layer (ATTL), deposited by rotational magnetron sputtering, presents a compact pinhole-free TiO2 thin film. Deposition of a compact TiO2 thin film on fluorine-doped tin oxide layers by ATTL did not change the surface roughness. To compare the introduced method, perovskite solar cell devices were fabricated and studied using different methods for the deposition of the TiO2 compact layers, which were used as common compact layer deposition methods. The ATTL method proposed considerable photovoltaic enhancement of perovskite solar cell performance (at least 22% enhancement in this work) by reducing the pinholes and sheet resistance of the TiO2 thin film. The improvement in the open-circuit voltage and the fill factor of the prepared devices using the ATTL method strongly confirmed the nature of the deposited pinhole-free TiO2 thin film. This method is shown to be an appropriate route for the reliable large-scale deposition of TiO2 compact layers.

High-Brightness Perovskite Light-Emitting Diodes Using a Printable Silver Microflake Contact.

Achieving efficient devices while maintaining a high fabrication yield is a key challenge in the fabrication of solution-processed, perovskite-based light-emitting diodes (PeLEDs). In this respect, pinholes in the solution-processed perovskite layers are a major obstacle. These are usually mitigated using organic electron-conducting planarization layers. However, these organic interlayers are unstable under applied bias in air and suffer from limited charge carrier mobility. In this work, we present a high brightness p-i-n PeLED based on a novel blade-coated silver microflake (SMF) rear electrode, which allows for a low-cost nanocrystalline ZnO inorganic electron-transporting layer to be used. This novel SMF contact is crucial for achieving high performance as it prevents the electrical shorting suffered when standard thermally evaporated silver rear contacts are used. The fabricated PeLEDs exhibit an excellent maximum luminance of 98,000 cd/m2, a maximum current efficiency of 22.3 cd/A, and a high external quantum efficiency of 4.6% under 5.9 V forward bias. The SMF rear contact can be printed and scaled at low cost to large areas and applied to flexible devices.

Enhancing Lifetime and Efficiency of Organic Solar Cell by Applying an In Situ Synthesized Low-Crystalline ZnO Layer.

By introducing an in situ synthesized low-crystalline ZnO (LC-ZnO) (amorphous) layer between the cathode and the active layer of PCPDTBT:CdSe solar cell {PCPDTBT: poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta [2,1-b:3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)]}, the device keeps more than 80 and 40 % of its initial lifetime after 180 and 360 days without any encapsulation, respectively. In this regard, 180 days is the highest lifetime achieved for polymer-based solar cells with direct configuration. In addition, the power conversion efficiency (PCE) is improved up to 70 % in the presence of the LC-ZnO interfacial layer. The LC-ZnO layer is synthesized during polymer annealing after solution-deposition of the precursor at a low temperature (140 °C) and a short time. Highly crystalline ZnO (HC-ZnO) nanoparticles are also synthesized and applied as an interfacial layer. The results show that the LC-ZnO is superior to the HC-ZnO in acting as cathode interfacial layer and moisture scavenger because of the high coverage and surface area provided by the in situ synthesis method.