Efficiency Enhancement of Organic Solar Cells by Using Shape‐Dependent Broadband Plasmonic Absorption in Metallic Nanoparticles

It is been widely reported that plasmonic effects in metallic nanomaterials can enhance light trapping in organix solar cells (OSCs). However, typical nanoparticles (NP) of high quality (i.e., mono‐dispersive) only possess a single resonant absorption peak, which inevitably limits the power conversion efficiency (PCE) enhancement to a narrow spectral range. Broadband plasmonic absorption is obviously highly desirable. In this paper, a combination of Ag nanomaterials of different shapes, including nanoparticles and nanoprisms, is proposed for this purpose. The nanomaterials are synthesized using a simple wet chemical method. Theoretical and experimental studies show that the origin of the observed PCE enhancement is the simultaneous excitation of many plasmonic low‐ and high‐order resonances modes, which are material‐, shape‐, size‐, and polarization‐dependent. Particularly for the Ag nanoprisms studied here, the high‐order resonances result in higher contribution than low‐order resonances to the absorption enhancement of OSCs through an improved overlap with the active material absorption spectrum. With the incorporation of the mixed nanomaterials into the active layer, a wide‐band absorption improvement is demonstrated and the short‐circuit photocurrent density (J_sc) improves by 17.91%. Finally, PCE is enhanced by 19.44% as compared to pre‐optimized control OSCs. These results suggest a new approach to achieve higher overall enhancement through improving broadband absorption.     

Enhanced Light‐Harvesting by Integrating Synergetic Microcavity and Plasmonic Effects for High‐Performance ITO‐Free Flexible Polymer Solar Cells

In this work, a high‐performance ITO‐free flexible polymer solar cell (PSC) is successfully described by integrating the plasmonic effect into the ITO‐free microcavity architecture. By carefully controlling the sizes of embedded Ag nanoprisms and their doping positons in the stratified device, a significant enhancement in power conversion efficiency (PCE) is shown from 8.5% (reference microcavity architecture) to 9.4% on flexible substrates. The well‐manipulated plasmonic resonances introduced by the embedded Ag nanoprisms with different LSPR peaks allow the complementary light‐harvesting with microcavity resonance in the regions of 400–500 nm and 600–700 nm, resulting in the substantially increased photocurrent. This result not only signifies that the spectral matching between the LSPR peaks of Ag nanoprisms and the relatively low absorption response of photoactive layer in the microcavity architecture is an effective strategy to enhance light‐harvesting across its absorption region, but also demonstrates the promise of tailoring two different resonance bands in a synergistic manner at desired wavelength region to enhance the efficiency of PSCs.     

Side‐Chain Engineering on Dopant‐Free Hole‐Transporting Polymers toward Highly Efficient Perovskite Solar Cells (20.19%)

A variety of dopant‐free hole‐transporting materials (HTMs) is developed to serve as alternatives to the typical dopant‐treated ones; however, their photovoltaic performance still falls far behind. In this work, the side chain of a polymeric HTM is engineered by partially introducing diethylene glycol (DEG) groups in order to simultaneously optimize the properties of both the bulk of the HTM layer and the HTM/perovskite interface. The intermolecular π–π stacking interaction in the HTM layer is unexpectedly weakened after the incorporation of DEG groups, whereas the lamellar packing interaction is strengthened. A doubled hole mobility is obtained when 3% of the DEG groups replace the original alkyl side chains, and a champion power conversion efficiency (PCE) of 20.19% (certified: 20.10%) is then achieved, which is the first report of values over 20% for dopant‐free organic HTMs. The device maintains 92.25% of its initial PCE after storing at ambient atmosphere for 30 d, which should be due to the enhanced hydrophobicity of the HTM film.     

Highly Stable and Efficient Perovskite Solar Cells with 22.0% Efficiency Based on Inorganic–Organic Dopant‐Free Double Hole Transporting Layers

Most of the high performance in perovskite solar cells (PSCs) have only been achieved with two organic hole transporting materials: 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9‐spirobifluorene (Spiro‐OMeTAD) and poly(triarylamine) (PTAA), but their high cost and low stability caused by the hygroscopic dopant greatly hinder the commercialization of PSCs. One effective alternative to address this problem is to utilize inexpensive inorganic hole transporting layer (i‐HTL), but obtaining high efficiency via i‐HTLs has remained a challenge. Herein, a well‐designed inorganic–organic double HTL is constructed by introducing an ultrathin polymer layer dithiophene‐benzene (DTB) between CuSCN and Au contact. This strategy not only enhances the hole extraction efficiency through the formation of cascaded energy levels, but also prevents the degradation of CuSCN caused by the reaction between CuSCN and Au electrode. Furthermore, the CuSCN layer also promotes the formation of a pinhole‐free and compact DTB over layer in the CuSCN/DTB structure. Consequently, the PSCs fabricated with this CuSCN/DTB layer achieves the power conversion efficiency of 22.0% (certified: 21.7%), which is among the top efficiencies for PSCs based on dopant‐free HTLs. Moreover, the fabricated PSCs exhibit high light stability under more than 1000 h of light illumination and excellent environmental stability at high temperature (85 °C) or high relative humidity (>60% RH).     

Plasmonic Electrically Functionalized TiO2 for High‐Performance Organic Solar Cells

Optical effects of the plasmonic structures and the materials effects of the metal nanomaterials have recently been individually studied for enhancing performance of organic solar cells (OSCs). Here, the effects of plasmonically induced carrier generation and enhanced carrier extraction of the carrier transport layer (i.e., plasmonic‐electrical effects) in OSCs are investigated. Enhanced charge extraction in TiO₂ as a highly efficient electron transport layer by the incorporation of metal nanoparticles (NPs) is proposed and demonstrated. Efficient device performance is demonstrated by using Au NPs incorporated TiO₂ at a plasmonic wavelength (560–600 nm), which is far longer than the originally necessary UV light. By optimizing the concentration ratio of the Au NPs in the NP‐TiO₂ composite, the performances of OSCs with various polymer active layers are enhanced and efficiency of 8.74% is reached. An integrated optical and electrical model, which takes into account plasmonic‐induced hot carrier tunneling probability and extraction barrier between TiO₂ and the active layer, is introduced. The enhanced charge extraction under plasmonic illumination is attributed to the strong charge injection of plasmonically excited electrons from NPs into TiO₂. The mechanism favors trap filling in TiO₂, which can lower the effective energy barrier and facilitate carrier transport in OSCs.     

Dithieno[3,2‐b:2′,3′‐d]pyrrol‐Cored Hole Transport Material Enabling Over 21% Efficiency Dopant‐Free Perovskite Solar Cells

Dopant‐free hole transport materials (HTMs) are essential for commercialization of perovskite solar cells (PSCs). However, power conversion efficiencies (PCEs) of the state‐of‐the‐art PSCs with small molecule dopant‐free HTMs are below 20%. Herein, a simple dithieno[3,2‐b:2′,3′‐d]pyrrol‐cored small molecule, DTP‐C6Th, is reported as a promising dopant‐free HTM. Compared with commonly used spiro‐OMeTAD, DTP‐C6Th exhibits a similar energy level, a better hole mobility of 4.18 × 10^?4 cm² V^?1 s^?1, and more efficient hole extraction, enabling efficient and stable PSCs with a dopant‐free HTM. With the addition of an ultrathin poly(methyl methacrylate) passivation layer and properly tuning the composition of the perovskite absorber layer, a champion PCE of 21.04% is achieved, which is the highest value for small molecule dopant‐free HTM based PSCs to date. Additionally, PSCs using the DTP‐C6Th HTM exhibit significantly improved long‐term stability compared with the conventional cells with the metal additive doped spiro‐OMeTAD HTM. Therefore, this work provides a new candidate and effective device engineering strategy for achieving high PCEs with dopant‐free HTMs.     

Over 16.7% Efficiency Organic‐Silicon Heterojunction Solar Cells with Solution‐Processed Dopant‐Free Contacts for Both Polarities

Realization of synchronous improvement in optical management and electrical engineering is necessary to achieve high‐performance photovoltaic device. However, inherent challenges are faced in organic‐silicon heterojunction solar cells (HSCs) due to the poor contact property of polymer on structured silicon surface. Herein, a remarkable efficiency boost from 12.6% to over 16.7% in poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)/n‐silicon (PEDOT:PSS/n‐Si) HSCs by independent optimization of hole‐/electron‐selective contacts only relying on solution‐based processes is realized. A bilayer PEDOT:PSS film with different functionalizations is utilized to synchronously realize conformal contact and effective carrier collection on textured Si surface, making the photogenerated carriers be well separated at heterojunction interface. Meanwhile, fullerene derivative is used as electron‐transporting layer at the rear n‐Si/Al interface to reduce the contact barrier. The study of carriers' transport and independent optimization on separately contacted layers may lead to an effective and simplified path to fabricate high‐performance organic‐silicon heterojunction devices.     

Unusually High Optical Transmission in Ca:Ag Blend Films: High‐Performance Top Electrodes for Efficient Organic Solar Cells

Highly transparent electrodes are demonstrated based on thermally evaporated calcium:silver blend thin–films, which show unusually high transmission well above the expectations from bulk material properties and thin film optics. These electrodes exhibit a low sheet resistance of 27.3 Ω/, combined with an extraordinarily high mean transmittance of 93.0% in the visible spectral range (σ_dc/σ_opt = 186.7), superior to the commonly used inorganic electrodes made from indium tin oxide (ITO). Additionally, the metal blend electrode is flexible, showing a constant sheet resistance down to a bending radius of 10 mm and can be employed on top of organic devices without causing damage to the organic material. The spontaneously formed unique microstructure of a polycrystalline Ag network with randomly distributed nanoapertures, surrounded by a calcium shell, enables broadband transmittance enhancement due to amplified plasmonic coupling. Consequently, top‐illuminated organic solar cells using such metal blend electrodes achieve a power conversion efficiency of 7.2% (which defines a new record for top illuminated organic solar cells) and even exceed the efficiency of similar bottom‐illuminated reference solar cells (6.9%) employing common ITO electrodes.     

PbTiO3 as Electron‐Selective Layer for High‐Efficiency Perovskite Solar Cells: Enhanced Electron Extraction via Tunable Ferroelectric Polarization

PbTiO₃ (PTO) is explored as a versatile and tunable electron‐selective layer (ESL) for perovskite solar cells. To demonstrate effectiveness of PTO for electron–hole separation and charge transfer, perovskite solar cells are designed and fabricated in the laboratory with the PTO as the ESL. The cells achieve a power conversion efficiency (PCE) of ≈12.28% upon preliminary optimization. It is found that the PTO ferroelectric layer can not only increase the PCE, but also tune the photocurrent via tuning PTO's ferroelectric polarization. Moreover, to understand the physical mechanism underlying the carrier transport by the ferroelectric polarization, the electronic structure of PTO/CH₃NH₃PbI₃ heterostructure is computed using the first‐principles methods, for which the triplet state is used to simulate charge transfer in the heterostructure. It is shown that the synergistic effect of type II band alignment and the specific ferroelectric polarization direction provide the effective extraction of electrons from the light absorber, while minimize recombination of photogenerated electron–hole pairs. Overall, the ferroelectric PTO is a promising and tunable ESL for optimizing electron transport in the perovskite solar cells. The design offers a different strategy for altering direction of carrier transport in solar cells.     

Carbon Counter Electrodes in Dye‐Sensitized and Perovskite Solar Cells

Developing highly effective and stable counter electrode (CE) materials to replace rare and expensive noble metals for dye‐sensitized and perovskite solar cells (DSC and PSC) is a research hotspot. Carbon materials are identified as the most qualified noble metal‐free CEs for the commercialization of the two photovoltaic devices due to their merits of low cost, excellent activity, and superior stability. Herein, carbonaceous CE materials are reviewed extensively with respect to the two devices. For DSC, a classified discussion according to the morphology is presented because electrode properties are closely related to the specific porosity or nanostructure of carbon materials. The pivotal factors influencing the catalytic behavior of carbon CEs are also discussed. For PSC, an overview of the new carbon CE materials is addressed comprehensively. Moreover, the modification techniques to improve the interfacial contact between the perovskite and carbon layers, aiming to enhance the photovoltaic performance, are also demonstrated. Finally, the development directions, main challenges, and coping approaches with respect to the carbon CE in DSC and PSC are stated.     

All‐Solution‐Processed Random Si Nanopyramids for Excellent Light Trapping in Ultrathin Solar Cells

Si nanopyramids have been suggested as one of the most promising Si nanostructures to realize high‐efficient ultrathin solar cells or photodetectors due to their low surface area enhancement and outstanding ability to enhance light absorption. However, the present techniques to fabricate Si nanopyramids are either complex or expensive. In parallel, disordered nanostructures are believed to be extremely effective to realize broadband light trapping for solar cells. Here, a simple and cost‐effective method is presented to form random Si nanopyramids based on an all‐solution process, the mechanism behind which is the successful transfer of the generation site of bubbles from Si surface to the introduced Ag nanoparticles so that OH^? can react with the entire Si surface to naturally form random and dense Si nucleus. For optical performance, it is experimentally demonstrated that the random Si nanopyramid textured ultrathin crystalline Si (c‐Si) can achieve light trapping approaching the Lambertian limit. Importantly, it is revealed, by numerical calculations, that random Si nanopyramids outperform periodic ones on broadband light absorption due to more excited optical resonance modes. The finding provides a new opportunity to improve the performance of ultrathin c‐Si solar cells with a simpler process and lower cost.     

Near‐Infrared Small Molecule Acceptor Enabled High‐Performance Nonfullerene Polymer Solar Cells with Over 13% Efficiency

One of the most promising approaches to achieve high‐performance polymer solar cells (PSCs) is to develop nonfullerene small molecule acceptors (SMAs) with an absorption extending to the near‐infrared (NIR) region. In this work, two novel SMAs, namely, BTTIC and BTOIC, are designed and synthesized, with optical bandgaps (E_g^opt) of 1.47 and 1.39 eV, respectively. Desipte the narrow E_g^opt, the PBDB‐T:BTTIC‐ and PBDB‐T:BTOIC‐based PSCs can maintain high V_OCs of over 0.90 and 0.86 V, respectively, with low energy losses (E_loss) < 0.6 eV. Meanwhile, due to the favorable morphology of the PBDB‐T:BTTIC blend, balanced carrier mobilities are achieved. The high external quantum efficiencies enable a high power conversion efficiency (PCE) up to 13.18% for the PBDB‐T:BTTIC‐based PSCs. In comparison, BTOIC shows an excessive crystallization propensity owing to its oxyalkyl side groups, which eventually leads to a relatively low PCE for the PBDB‐T:BTOIC‐based PSCs. Overall, this work provides insights into the design of novel NIR‐absorbing SMAs for nonfullerene PSCs.     

Additive‐Free Bulk‐Heterojuction Solar Cells with Enhanced Power Conversion Efficiency,Comprising a Newly Designed Selenophene‐Thienopyrrolodione Copolymer

Bulk‐heterojunction solar cells are reported with an enhanced power conversion efficiency (PCE) based on a newly designed semiconducting selenophene‐thienopyrrolodione (TPD) copolymer blended with [6,6]‐phenyl C₇₁ butyric acid methyl‐ester. The solar cells are fabricated using simple solution processing (implying low‐cost fabrication). The relatively deep highest occupied molecular orbital (HOMO) level leads to a correspondingly high open‐circuit voltage of 0.88 V. The PCE approaches 5.8% when Clevious P VP AI4083 is used as the hole‐transport interlayer, with an optimized active layer thickness of approximately 95 nm, and a donor‐acceptor blend ratio of 1:1. A fill factor (FF) of 0.62 is achieved. The use of additives does not seem to be beneficial in this blended system, due to the achievement of proper phase separation in the as‐cast films. Also, the BHJ devices with a 3% ratio of a 1‐chloronaphthalene (CN) additive exhibit much more severe oxidative degradation from the decreased FF with a high series resistance than BHJ devices without additive. The selenophene‐TPD based BHJ solar cell is a promising candidate for high‐performance single cells with a low‐cost additive‐free fabrication and a long‐term stable operation.     

Dopant‐Free Spiro‐Triphenylamine/Fluorene as Hole‐Transporting Material for Perovskite Solar Cells with Enhanced Efficiency and Stability

Chemical doping is often used to enhance electric conductivity of the conjugated molecule as hole‐transporting material (HTM) for the application in optoelectronics. However, chemical dopants can promote ion migration at the electrical field, which deteriorates the device efficiency as well as increases the fabrication cost. Here, two star HTMs, namely 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine) 9,9′‐spirobifluorene (Spiro‐OMeTAD) and poly(triarylamine) are subjeted to chemical combination to yield dopant‐free N2,N2,N2′,N2′,N7,N7,N7′,N7′‐octakis(4‐methoxyphenyl)‐10‐phenyl‐10H‐spiro[acridine‐9,9′‐fluorene]‐2,2′,7,7′‐tetraamine (SAF‐OMe). The power conversion efficiencies (PCEs) of 12.39% achieved by solar cells based on pristine, dopant‐free SAF‐OMe are among the highest reported for perovskite solar cells and are even comparable to devices based on chemically doped Spiro‐OMeTAD (14.84%). Moreover, using a HTM comprised of SAF‐OMe with an additional dopant results in a record PCE of 16.73%. Compared to Spiro‐OMeTAD‐based devices, SAF‐OMe significantly improves stability.     

All‐Solution‐Processed Indium‐Free Transparent Composite Electrodes based on Ag Nanowire and Metal Oxide for Thin‐Film Solar Cells

Fully solution‐processed Al‐doped ZnO/silver nanowire (AgNW)/Al‐doped ZnO/ZnO multi‐stacked composite electrodes are introduced as a transparent, conductive window layer for thin‐film solar cells. Unlike conventional sol–gel synthetic pathways, a newly developed combustion reaction‐based sol–gel chemical approach allows dense and uniform composite electrodes at temperatures as low as 200 °C. The resulting composite layer exhibits high transmittance (93.4% at 550 nm) and low sheet resistance (11.3 Ω sq^‐1), which are far superior to those of other solution‐processed transparent electrodes and are comparable to their sputtered counterparts. Conductive atomic force microscopy reveals that the multi‐stacked metal‐oxide layers embedded with the AgNWs enhance the photocarrier collection efficiency by broadening the lateral conduction range. This as‐developed composite electrode is successfully applied in Cu(In_1‐x,Ga_x)S₂ (CIGS) thin‐film solar cells and exhibits a power conversion efficiency of 11.03%. The fully solution‐processed indium‐free composite films demonstrate not only good performance as transparent electrodes but also the potential for applications in various optoelectronic and photovoltaic devices as a cost‐effective and sustainable alternative electrode.     

An Effective Approach for High‐Efficiency Photoelectrochemical Solar Cells by Using Bifunctional DNA Molecules Modified Photoanode

This paper firstly reports the effect of deoxyribonucleic acid (DNA) molecules extracted from chickpea and wheat plants on the injection/recombination of photogenerated electrons and sensitizing ability of dye‐sensitized solar cells (DSSCs). These high‐yield DNA molecules are applied as both linker bridging unit as well as thin tunneling barrier (TTB) at titanium dioxide (TiO₂ )/dye interface, to build up high‐efficient DSSCs. With its favorable energy levels, effective linker bridging role, and double helix structure, bifunctional DNA modifier shows an efficient electron injection, suppressed charge recombination, longer electron lifetime, and higher light harvesting efficiency, which leads to higher photovoltaic performance. In particular, a photoconversion efficiency (PCE) of 9.23% is achieved by the binary chickpea and wheat DNA‐modified TiO₂ (CW@TiO₂) photoanode. Furthermore, time‐resolved fluorescence spectroscopy measurements confirm a better electron transfer kinetics for DNA‐modified TiO₂ photoanodes, implying a higher electron transfer rate (k_ET). This work highlights a great contribution for the photoanodes that are linked with DNA molecule, which act as both bridging unit and TTB to control the charge recombination and injection dynamics, and hence, boost the photovoltaic performance in the DSSCs.     

Side Group Engineering of Small Molecular Acceptors for High‐Performance Fullerene‐Free Polymer Solar Cells: Thiophene Being Superior to Selenophene

Side group of ITIC‐like small molecular acceptor (SMA) plays a critical role in crystallization property. In this article, two new SMAs with n‐hexylthienyl and n‐hexylselenophenyl as side chain, namely ITCPTC‐Th and ITCPTC‐Se, are designed and synthesized by employing newly developed thiophene‐fused ending group (CPTCN). And thiophene and selenophene side group substituted effects of SMA‐based fullerene‐free polymer solar cells (PSCs) are investigated. A stronger σ‐inductive effect between selenophene side group and electron‐donating backbone endows ITCPTC‐Se with better optical absorption and higher LUMO level, ITCPTC‐Th‐based PSCs deliver a higher power conversion efficiency of 10.61%. Charge transport and collection, recombination loss mechanism, and morphology of blend films are intensively studied. These results confirm that side group substituted effects of SMAs are multiple and thiophene is a superior option to selenophene as aromatic side group of ITIC‐like SMAs.     

Revealing the Impact of F4‐TCNQ as Additive on Morphology and Performance of High‐Efficiency Nonfullerene Organic Solar Cells

Fluorinated molecule 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) and its derivatives have been used in polymer:fullerene solar cells primarily as a dopant to optimize the electrical properties and device performance. However, the underlying mechanism and generality of how F4‐TCNQ affects device operation and possibly the morphology is poorly understood, particularly for emerging nonfullerene organic solar cells. In this work, the influence of F4‐TCNQ on the blend film morphology and photovoltaic performance of nonfullerene solar cells processed by a single halogen‐free solvent is systematically investigated using a set of morphological and electrical characterizations. In solar cells with a high‐performance polymer:small molecule blend FTAZ:IT‐M, F4‐TCNQ has a negligibly small effect on the molecular packing and surface characteristics, while it clearly affects the electronic properties and mean‐square composition variation of the bulk. In comparison to the control devices with an average power conversion efficiency (PCE) of 11.8%, inclusion of a trace amount of F4‐TCNQ in the active layer has improved device fill factor and current density, which has resulted into a PCE of 12.4%. Further increase in F4‐TCNQ content degrades device performance. This investigation aims at delineating the precise role of F4‐TCNQ in nonfullerene bulk heterojunction films, and thereby establishing a facile approach to fabricate highly optimized nonfullerene solar cells.     

Fully High‐Temperature‐Processed SnO2 as Blocking Layer and Scaffold for Efficient,Stable, and Hysteresis‐Free Mesoporous Perovskite Solar Cells

Planar perovskite solar cells (PSCs) based on low‐temperature‐processed (LTP) SnO₂ have demonstrated excellent photovoltaic properties duo to the high electron mobility, wide bandgap, and suitable band energy alignment of LTP SnO₂. However, planar PSCs or mesoporous (mp) PSCs based on high‐temperature‐processed (HTP) SnO₂ show much degraded performance. Here, a new strategy with fully HTP Mg‐doped quantum dot SnO₂ as blocking layer (bl) and a quite thin SnO₂ nanoparticle as mp layer are developed. The performances of both planar and mp PSCs has been greatly improved. The use of Mg‐SnO₂ in planar PSCs yields a high‐stabilized power conversion efficiency (PCE) of close to 17%. The champion of mp cells exhibits hysteresis free and stable performance with a high‐stabilized PCE of 19.12%. The inclusion of thin mp SnO₂ in PSCs not only plays a role of an energy bridge, facilitating electrons transfer from perovskite to SnO₂ bl, but also enhances the contact area of SnO₂ with perovskite absorber. Impedance analysis suggests that the thin mp layer is an “active scaffold” selectively collecting electrons from perovskite and can eliminate hysteresis and effectively suppress recombination. This is an inspiring advance toward high‐performance PSCs with HTP mp SnO₂.     

High‐Performance Metal‐Free Solar Cells Using Stamp Transfer Printed Vapor Phase Polymerized Poly(3,4‐Ethylenedioxythiophene) Top Anodes

The use of vapor phase polymerized poly(3,4‐ethylenedioxythiophene) (VPP‐PEDOT) as a metal‐replacement top anode for inverted solar cells is reported. Devices with both i) standard bulk heterojunction blends of poly(3‐hexylthiophene) (P3HT) donor and 1‐(3‐methoxycarbonyl)‐propyl‐1‐phenyl‐(6,6)C₆₀ (PCBM) soluble fullerene acceptor and ii) hybrid inorganic/organic TiO₂/P3HT acceptor/donor active layers are studied. Stamp transfer printing methods are used to deposit both the VPP‐PEDOT top anode and a work function enhancing PEDOT:polystyrenesulphonate (PEDOT:PSS) interlayer. The metal‐free devices perform comparably to conventional devices with an evaporated metal top anode, yielding power conversion efficiencies of 3% for bulk heterojunction blend and 0.6% for organic/inorganic hybrid structures. These encouraging results suggest that stamp transfer printed VPP‐PEDOT provides a useful addition to the electrode materials tool‐box available for low temperature and non‐vacuum solar cell fabrication.