Analytical Study of Solution-Processed Tin Oxide as Electron Transport Layer in Printed Perovskite Solar Cells

Solution‐processed tin oxide (SnO$_{x}$ ) electron transport layers demonstrate excellent performance in various optoelectronic devices and offer the ease of facile and low cost deposition by various printing techniques. The most common precursor solution for the preparation of SnO$_{x}$ thin films is SnCl$_{2}$ dissolved in ethanol. In order to elucidate the mechanism of the precursor conversion at different annealing temperatures and the optoelectronic performance of the SnO$_{x}$ electron transport layer, phonon and vibrational infrared and photoelectron spectroscopies as well as atomic force microscopy are used to probe the chemical, physical, and morphological properties of the SnO$_{x}$ thin films. The influence of two different solvents on the layer morphology of SnO$_{x}$ thin films is investigated. In both cases, an increasing annealing temperature not only improves the structural and chemical properties of solution‐processed SnO$_{x}$, but also reduces the concentration of tin hydroxide species in the bulk and on the surface of these thin films. As a prototypical example for the high potential of printed SnO$_{x}$ layers for solar cells, high performance perovskite solar cells with a stabilized power conversion efficiency of over 15% are presented

Electron Beam Evaporated Nickel Oxide Hole Transport Layers for Perovskite Based Photovoltaics

High amp; 8208;quality charge carrier transport materials are of key importance for stable and efficient perovskite amp; 8208;based photovoltaics. This work reports on electron amp; 8208;beam amp; 8208;evaporated nickel oxide NiOx layers, resulting in stable power conversion efficiencies PCEs of up to 18.5 when integrated into solar cells employing inkjet amp; 8208;printed perovskite absorbers. By adding oxygen as a process gas and optimizing the layer thickness, transparent and efficient NiOx hole transport layers HTLs are fabricated, exhibiting an average absorptance of only 1 . The versatility of the material is demonstrated for different absorber compositions and deposition techniques. As another highlight of this work, all amp; 8208;evaporated perovskite solar cells employing an inorganic NiOx HTL are presented, achieving stable PCEs of up to 15.4 . Along with good PCEs, devices with electron amp; 8208;beam amp; 8208;evaporated NiOx show improved stability under realistic operating conditions with negligible degradation after 40 h of maximum power point tracking at 75 C. Additionally, a strong improvement in device stability under ultraviolet radiation is found if compared to conventional perovskite solar cell architectures employing other metal oxide charge transport layers e.g., titanium dioxide . Finally, an all amp; 8208;evaporated perovskite solar mini amp; 8208;module with a NiOx HTL is presented, reaching a PCE of 12.4 on an active device area of 2.3 cm