PtCoFe Nanowire Cathodes Boost Short‐Circuit Currents of Ru(II)‐Based Dye‐Sensitized Solar Cells to a Power Conversion Efficiency of 12.29%

PtCoFe nanowires with different alloying compositions are chemically prepared and acted as counter electrodes (CEs) in dye‐sensitized solar cells (DSSCs) with Ru(II)‐based dyes. Due to their superior reduction activity, PtCoFe nanowires with rich (111) facets enhance the performance of DSSCs. Hence, N719 DSSCs with PtCoFe nanowires, respectively, produce better power conversion efficiency (PCE) of 8.10% for Pt₃₃Co₂₄Fe₄₃ nanowire, 8.33% for Pt₇₄Co₁₂Fe₁₄ nanowire, and 9.26% for Pt₄₉Co₂₃Fe₂₈ nanowire in comparison to the PCE of Pt CE (7.32%). Further, the PRT‐22 DSSC with Pt₄₉Co₂₃Fe₂₈ nanowire exhibits a maximum PCE of 12.29% with a certificated value of 12.0%, which surpass the previous PCE record of the DSSCs with Ru(II)‐based dyes. The photovoltaic and electrochemical results reveal the composition‐dependent activity along with a volcano‐shaped trend in the I^?/ redox reaction. Theoretical work on the adsorption energies of I₂, the desorption energies of I^?, and the corresponding absolute energy demonstrates that the reduction activity followed in the order of Pt₄₉Co₂₃Fe₂₈(111) plane > Pt₇₄Co₁₂Fe₁₄(111) plane > Pt₃₃Co₂₄Fe₄₃(111) plane, proving Pt₄₉Co₂₃Fe₂₈ nanowire to be a superior cathode material for DSSCs.     

Biohybrid Photoprotein‐Semiconductor Cells with Deep‐Lying Redox Shuttles Achieve a 0.7 V Photovoltage

Photosynthetic proteins transduce sunlight into biologically useful forms of energy through a photochemical charge separation that has a close to 100% quantum efficiency, and there is increasing interest in their use as sustainable materials in biohybrid devices for solar energy harvesting. This work explores a new strategy for boosting the open circuit voltage of photoelectrochemical cells based on a bacterial photosynthetic pigment‐protein by employing highly oxidizing redox electrolytes in conjunction with an n‐type silicon anode. Illumination generates electron–hole pairs in both the protein and the silicon electrode, the two being connected by the electrolyte which transfers electrons from the reducing terminal of the protein to photogenerated holes in the silicon valence band. A high open circuit voltage of 0.6 V is achieved with the most oxidizing electrolyte 2,2,6,6‐tetramethyl‐1‐piperidinyloxy, and this is further improved to 0.7 V on surface modification of the silicon electrode to increase its surface area and reduce reflection of incident light. The photovoltages produced by these biohybrid protein/silicon cells are comparable to those typical of silicon heterojunction and dye‐sensitized solar cells.     

Diphenylamine‐Substituted Carbazole‐Based Hole Transporting Materials for Perovskite Solar Cells: Influence of Isomeric Derivatives

A series of new branched hole transporting materials (HTMs) containing two diphenylamine‐substituted carbazole fragments linked by a nonconjugated methylenebenzene unit is synthesized and tested in perovskite solar cells. Synthesis of the investigated materials is performed by a simple two‐step synthetic procedure providing a target product in high yield. The isolated materials demonstrate good thermal stability and majority of the investigated compounds exist in an amorphous state, which is advantageous as there is no risk of crystallization directly in the film. The highest charge drift mobility of µ₀ = 4 × 10^?4 cm² V^?1 s^?1, measured at weak electric fields, is by ca. one order of magnitude higher than that of Spiro‐OMeTAD under identical conditions. From the perovskite solar cell testing results, it can be seen that performance of two new HTMs ( V885 and V911 ) is on a par with Spiro‐OMeTAD. Due to the ease of synthesis, good thermal, optical and photophysical properties, this type of molecules hold great promise for practical application in commercial perovskite solar cells.     

Combination of Hybrid CVD and Cation Exchange for Upscaling Cs‐Substituted Mixed Cation Perovskite Solar Cells with High Efficiency and Stability

Mixed cation hybrid perovskites such as Cs_xFA_1?xPbI₃ are promising materials for solar cell applications, due to their excellent photoelectronic properties and improved stability. Although power conversion efficiencies (PCEs) as high as 18.16% have been reported, devices are mostly processed by the anti‐solvent method, which is difficult for further scaling‐up. Here, a method to fabricate Cs_xFA_1?xPbI₃ by performing Cs cation exchange on hybrid chemical vapor deposition grown FAPbI₃ with the Cs⁺ ratio adjustable from 0 to 24% is reported. The champion perovskite module based on Cs_0.07FA_0.93PbI₃ with an active area of 12.0 cm² shows a module PCE of 14.6% and PCE loss/area of 0.17% cm^?2, demonstrating the significant advantage of this method toward scaling‐up. This in‐depth study shows that when the perovskite films prepared by this method contain 6.6% Cs⁺ in bulk and 15.0% at the surface, that is, Cs_0.07FA_0.93PbI₃, solar cell devices show not only significantly increased PCEs but also substantially improved stability, due to favorable energy level alignment with TiO₂ electron transport layer and spiro‐MeOTAD hole transport layer, increased grain size, and improved perovskite phase stability.