In this work, we report efficient semitransparent perovskite solar cells using solution-processed silver nanowires (AgNWs) as top electrodes. A thin layer of zinc oxide nanoparticles is introduced beneath the AgNWs, which fulfills two essential functionalities: it ensures ohmic contact between the PC 60 BM and the AgNWs and it serves as a physical foundation that enables the solution-deposition of AgNWs without causing damage to the underlying perovskite. The as-fabricated semitransparent perovskite cells show a high fill factor of 66.8%, V oc = 0.964 V, J sc = 13.18 mA cm −2 , yielding an overall efficiency of 8.49% which corresponds to 80% of the reference devices with reflective opaque electrodes.Inorganic-organic halide perovskite solar cells have recently emerged as a promising photovoltaic technology due to their high efficiencies and low-cost processing potential. [1][2][3][4] The exceptional optoelectronic properties of the perovskite crystals such as high carrier mobility and long charge diffusion length promise highly efficient charge separation. 5,6 These intriguing characteristics make perovskites ideal materials for photovoltaic applications. Since the first device demonstration in 2009, power conversion efficiency (PCE) of perovskite solar cells processed by both vacuum-deposition and solutionprocessing has surged to over 15%. 2,4,[7][8][9] The continuous and fast progress in the research related to perovskite solar devices has established them as a serious contestant to the traditional silicon-based panels.Together with the considerable efforts devoted to pursuing high efficiencies via improved crystallization of perovskite and searching for low-cost interface materials, 4,10-13 aesthetic semitransparent perovskite solar cells have been simultaneously receiving growing attention because of their specific application in transparent architectures, 14-17 such as windows, rooftops, greenhouses and other fashion elements. To achieve efficient semitransparent perovskite devices, both the anode and the cathode of the devices should be highly transparent and conductive in order to minimize the optical and resistance losses. To date, several studies have reported semitransparent perovskite solar cells, but most of these devices employed thin metal films (Al, Ag, Au) as top electrodes which were fabricated based on energy-intensive evaporation processes. [15][16][17] It is well known that, in addition to low-cost materials, the cost reduction of photovoltaic devices substantially depends on the ability to use high-throughput coating techniques in combination with roll-to-roll processing. 18 Despite its importance, however, less attention has been paid to the exploration of solution-processable transparent electrodes for perovskite solar cells. Carbon based materials have received much attention for use as conducting electrodes for perovskite solar cells, due to their low-cost and high stability. 14,19,20 For example, Li et al.have recently reported semitransparent perovskite solar cells using carbon nanotub...

Perovskite hybrid solar cells (pero-HSCs) were demonstrated to be amongst the most promising candidates within the emerging photovoltaic materials with respect to their power conversion efficiency (PCE) and inexpensive fabrication. Further PCE enhancement mainly relies on minimizing the interface losses via interface engineering and the quality of the perovskite film. Here we demonstrate that the PCEs of pero-HSCs is significantly increased to 14.0% by incorporation of a solution-processed perylene diimide (PDINO) as cathode interface layer between [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) layer and the top Ag electrode. Notably, for PDINO based devices, prominent PCEs over 13% are achieved within a wide range of the PDINO thickness (5-24 nm). Without the PDINO layer, the best PCE of the reference PCBM/Ag device was only 10.0%. The PCBM/PDINO/Ag devices also outperformed the PCBM/ZnO/Ag devices (11.3%) with the well-established zinc oxide (ZnO) cathode interface layer. This enhanced performance is due to the formation of a highly qualitative contact between PDINO and the top Ag electrode, leading to reduced series resistance (R s ) and enhanced shunt resistance (R sh ) values. This study opens the door for the integration of a new class of easy-accessible, solution-processed high performance interfacial materials for pero-HSCs.

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.

over 30% detailed balance limiting efficiency, as well as to its earth-abundant and environment-benign constituents. [1-3] The increase in power conversion efficiency to a record of 12.6% in the last decade has demonstrated the huge potential of these materials. [4,5] However, as one of the most complicated compound semiconductors, kesterite has much more intricate defect chemistry than its counterparts, Cu(In,Ga)Se 2 (CIGS) and CdTe, [6-8] making the control of intrinsic defects a major challenge. Deep intrinsic defects like Sn Zn antisites and related [Cu Zn +Sn Zn ] clusters act as deep recombination centers, leading to the short carrier lifetime. [7,9,10] Additionally, the large population of defect clusters like [2Cu Zn +Sn Zn ] introduces considerable potential (i.e., band or electrostatic) fluctuation. [11] Consequently, the performance of CZTSSe solar cells are currently stagnated by the large open-circuit voltage (V OC) deficit. [12,13] To address the detrimental intrinsic defects and defect clusters in CZTSSe absorber, multiple strategies have been employed. As suggested by the first-principle calculations, the formation energy of intrinsic defects and Kesterite-based Cu 2 ZnSn(S,Se) 4 semiconductors are emerging as promising materials for low-cost, environment-benign, and high-efficiency thin-film photo voltaics. However, the current state-of-the-art Cu 2 ZnSn(S,Se) 4 devices suffer from cation-disordering defects and defect clusters, which generally result in severe potential fluctuation, low minority carrier lifetime, and ultimately unsatisfactory performance. Herein, critical growth conditions are reported for obtaining high-quality Cu 2 ZnSnSe 4 absorber layers with the formation of detrimental intrinsic defects largely suppressed. By controlling the oxidation states of cations and modifying the local chemical composition, the local chemical environment is essentially modified during the synthesis of kesterite phase, thereby effectively suppressing detrimental intrinsic defects and activating desirable shallow acceptor Cu vacancies. Consequently, a confirmed 12.5% efficiency is demonstrated with a high V OC of 491 mV, which is the new record efficiency of pure-selenide Cu 2 ZnSnSe 4 cells with lowest V OC deficit in the kesterite family by E g /q-Voc. These encouraging results demonstrate an essential route to overcome the long-standing challenge of defect control in kesterite semiconductors, which may also be generally applicable to other multinary compound semiconductors.

As perovskite solar cells (PSCs) are highly efficient, demonstration of high‐performance printed devices becomes important. 2D/3D heterostructures have recently emerged as an attractive way to relieving the film inhomogeneity and instability in perovskite devices. In this work, a 2D/3D ensemble with 2D perovskites self‐assembled atop 3D methylammonium lead triiodide (MAPbI3) via a one‐step printing process is shown. A clean and flat interface is observed in the 2D/3D bilayer heterostructure for the first time. The 2D perovskite capping layer significantly suppresses nonradiative charge recombination, resulting in a marked increase in open‐circuit voltage (VOC) of the devices by up to 100 mV. An ultrahigh VOC of 1.20 V is achieved for MAPbI3 PSCs, corresponding to 91% of the Shockley–Queisser limit. Moreover, notable enhancement in light, thermal, and moisture stability is obtained as a result of the protective barrier of the 2D perovskites. These results suggest a viable approach for scalable fabrication of highly efficient perovskite solar cells with enhanced environmental stability.

The concept of mixed 2D/3D heterostructures has emerged as an effective method for improving the stability of lead halide perovskite solar cells, which has been, however, rarely reported in lead–tin (Pb–Sn) mixed perovskite devices. Here, we report a scalable process for depositing mixed 2D/3D Pb–Sn perovskite solar cells that deliver remarkably enhanced efficiency and stability compared to their 3D counterparts. The incorporation of a small amount (3.75%) of an organic cation 2-(4-fluorophenyl)­ethylammonium iodide induces the growth of highly oriented Pb–Sn perovskite crystals perpendicularly aligned with the substrate. Moreover, for the first time, phase segregation is observed in pristine 3D Pb–Sn perovskites, which is suppressed due to the presence of the 2D perovskites. Accordingly, a high current density of 28.42 mA cm–2 is obtained due to the markedly enhanced spectral response and charge extraction. Eventually, mixed 2D/3D Pb–Sn perovskite devices with a band gap of 1.33 eV yield efficiencies as high as 17.51% and in parallel exhibit good stability.

Emerging photovoltaics (PVs) focus on a variety of applications complementing large scale electricity generation. Organic, dye-sensitized, and some perovskite solar cells are considered in building integration, greenhouses, wearable, and indoor applications, thereby motivating research on flexible, transparent, semitransparent, and multi-junction PVs. Nevertheless, it can be very time consuming to find or develop an up-to-date overview of the stateof-the-art performance for these systems and applications. Two important resources for recording research cells efficiencies are the National Renewable Energy Laboratory chart and the efficiency tables compiled biannually by Martin Green and colleagues. Both publications provide an effective coverage over the established technologies, bridging research and industry. An alternative approach is proposed here summarizing the best reports in the diverse research subjects for emerging PVs. Best performance parameters are provided as a function of the photovoltaic bandgap energy for each technology and application, and are put into perspective using, e.g., the Shockley-Queisser limit. In all cases, the reported data correspond to published and/or properly described certified results, with enough details provided for prospective data reproduction. Additionally, the stability test energy yield is included as an analysis parameter among state-of-the-art emerging PVs.

Metal halide perovskite solar cells (PSCs) have raised considerable scientific interest due to their high cost‐efficiency potential for photovoltaic solar energy conversion. As PSCs already are meeting the efficiency requirements for renewable power generation, more attention is given to further technological barriers as environmental stability and reliability. However, the most major obstacle limiting commercialization of PSCs is the lack of a reliable and scalable process for thin film production. Here, a generic crystallization strategy that allows the controlled growth of highly qualitative perovskite films via a one‐step blade coating is reported. Through rational ink formulation in combination with a facile vacuum‐assisted precrystallization strategy, it is possible to produce dense and uniform perovskite films with high crystallinity on large areas. The universal application of the method is demonstrated at the hand of three typical perovskite compositions with different band gaps. P‐i‐n perovskite solar cells show fill factors up to 80%, underpinning the statement of the importance of controlling crystallization dynamics. The methodology provides important progress toward the realization of cost‐effective large‐area perovskite solar cells for practical applications.