A major bottleneck delaying the further commercialization of thin-film solar cells based on hybrid organohalide lead perovskites is interface loss in state-of-the-art devices. We present a generic interface architecture that combines solution-processed, reliable, and cost-efficient hole-transporting materials without compromising efficiency, stability, or scalability of perovskite solar cells. Tantalum-doped tungsten oxide (Ta-WO )/conjugated polymer multilayers offer a surprisingly small interface barrier and form quasi-ohmic contacts universally with various scalable conjugated polymers. In a simple device with regular planar architecture and a self-assembled monolayer, Ta-WO -doped interface-based perovskite solar cells achieve maximum efficiencies of 21.2% and offer more than 1000 hours of light stability. By eliminating additional ionic dopants, these findings open up the entire class of organics as scalable hole-transporting materials for perovskite solar cells.

Fundamental advances to increase the efficiency as well as stability of organic photovoltaics (OPVs) are achieved by designing ternary blends, which represents a clear trend toward multicomponent active layer blends. The development of high‐throughput and autonomous experimentation methods is reported for the effective optimization of multicomponent polymer blends for OPVs. A method for automated film formation enabling the fabrication of up to 6048 films per day is introduced. Equipping this automated experimentation platform with a Bayesian optimization, a self‐driving laboratory is constructed that autonomously evaluates measurements to design and execute the next experiments. To demonstrate the potential of these methods, a 4D parameter space of quaternary OPV blends is mapped and optimized for photostability. While with conventional approaches, roughly 100 mg of material would be necessary, the robot‐based platform can screen 2000 combinations with less than 10 mg, and machine‐learning‐enabled autonomous experimentation identifies stable compositions with less than 1 mg.

substrates accounts for 90% of the total energy required for manufacturing OPV. [ 8 ] To achieve ITO-free and fully solutionprocessed organic solar cells, the choice and processing of the anode and cathode electrodes are two challenges which require different considerations. Solutionprocessed bottom electrodes based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), AgNW and metallic grid electrodes are constantly narrowing the gap to ITO. [9][10][11][12][13][14][15][16] The main challenge for fully solution-processed devices remains the combination of a bottom and a top electrode, because the very thin and/ or soft underlying layers have to resist the solution deposition of the top electrode. Recently, solution-processed graphene, [ 17 ] AgNW, [ 18 , -21 ] silver nanoparticles [ 22 ] and PEDOT:PSS [ 23,24 ] were investigated as transparent top electrodes for organic solar cells. However, devices with incorporation of these top electrodes suffered either from the inferior optoelectronic properties of the electrodes or their multi-transfer processing procedure. On the other hand, aesthetic (semi-)transparent solar cells with special applications in windows, foldable curtains, buildings and clothes, etc., have recently gained much scientifi c attention and are considered to be the highest priority market for OPV. [ 25 ] We report here on materials and processes for reliable and cost-effi cient processing of ITO-free semitransparent organic solar cells from solution. Fully solution-processed organic solar Organic photovoltaic (OPV) solar cells that can be simply processed from solution are in the focus of the academic and industrial community because of their enormous potential to reduce cost. One big challenge in developing a fully solution-processed OPV technology is the design of a well-performing electrode system, allowing the replacement of ITO. Several solution-processed electrode systems were already discussed, but none of them could match the performance of ITO. Here, we report effi cient ITO-free and fully solution-processed semitransparent inverted organic solar cells based on silver nanowire (AgNW) electrodes. To demonstrate the potential of these AgNW electrodes, they were employed as both the bottom and top electrodes. Record devices achieved fi ll factors as high as 63.0%, which is comparable to ITO based reference devices. These results provide important progress for fully printed organic solar cells and indicate that ITO-free, transparent as well as non-transparent organic solar cells can indeed be fully solution-processed without losses.

Figure 7 . Photograph of the semitransparent devices discussed in this manuscript. The performance of the device on the left is presented in Figure 5a, the EQE for the device on the right in Figure 5b and its performance in Figure 6. The high transmittance of the electrode layer makes it diffi cult to identify them, but underlines the outstanding optical properties of the NW electrode. Each substrate contains six separate devices.