Heterojunction Photovoltaic Devices Research Articles

Efficient organic photovoltaic cells based on thiazolothiazole and benzodithiophene copolymers with π‐conjugated bridges

ABSTRACTNew donor–π–acceptor (D–π–A) type conjugated copolymers, poly[(4,8‐bis((2‐hexyldecyl)oxy)benzo[1,2‐b:4,5‐b′]dithiophene)‐alt‐(2,5‐bis(4‐octylthiophen‐2‐yl)thiazolo[5,4‐d]thiazole)] (PBDT‐tTz), and poly[(4,8‐bis((2‐hexyldecyl)oxy)benzo[1,2‐b:4,5‐b′]dithiophene)‐alt‐(2,5‐bis(6‐octylthieno[3,2‐b]thiophen‐2‐yl)thiazolo[5,4‐d]thiazole)] (PBDT‐ttTz) were synthesized and characterized with the aim of investigating their potential applicability to organic photovoltaic active materials. While copolymer PBDT‐tTz showed a zigzagged non‐linear structure by thiophene π‐bridges, PBDT‐ttTz had a linear molecular structure with thieno[3,2‐b]thiophene π‐bridges. The optical, electrochemical, morphological, and photovoltaic properties of PBDT‐tTz and PBDT‐ttTz were systematically investigated. Furthermore, bulk heterojunction photovoltaic devices were fabricated by using the synthesized polymers as p‐type donors and [6,6]‐phenyl‐C71‐butyric acid methyl ester as an n‐type acceptor. PBDT‐ttTz showed a high power conversion efficiency (PCE) of 5.21% as a result of the extended conjugation arising from the thienothiophene π‐bridges and enhanced molecular ordering in the film state, while PBDT‐tTz showed a relatively lower PCE of 2.92% under AM 1.5 G illumination (100 mW/cm2). © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1978–1988

Interface properties of ITO/n-Si heterojunction solar cell: Quantum tunneling, passivation and hole-selective contacts

In this report, a numerical simulation for ITO/n-Si based hetero-junction (ISHJ) photovoltaic device has been carried out by using AFORS-HET software and a proper model, in which the naturally derived interface layer with a ternary-like hybrid of a-SiOx(In) is assumed to be a double stacks of 1.2 nm quasi p type semiconductor and 0.2 nm insulator as buffer layer. The negative charge centers, in the range of >1 × 1017 cm−3, associated with oxygen vacancies and indium-ion correlative ternary hybrid in the intermediate region play multi-roles, including field effect passivation, inducing inversion layer and acting selective contacts to a certain extent. The simulation results manifest that the intermediate region behaviors as a semiconductor material with a wide band gap of 2.06 eV, which is suitable for the transport of hole and an induced quasi p-n junction. Additionally, the simulated J-V curve arisen from the key opto-electric parameters of the device by the simulation agrees with the experimental one with a high fill factor of 74.2% well.

Bifunctional Hybrid a-SiO x(Mo) Layer for Hole-Selective and Interface Passivation of Highly Efficient MoO x/a-SiO x(Mo)/n-Si Heterojunction Photovoltaic Device.

The promising n-Si-based solar cell is constructed for the purpose of realizing hole- and electron-selective passivating contact, using a textured front indium tin oxide/MoO x structure and a planar rear a-SiO x/poly(Si(n+)) structure severally. The simple MoO x/n-Si heterojunction device obtains an efficiency of 16.7%. It is found that the accompanying ternary hybrid SiO x(Mo) interlayer (3.5-4.0 nm) is formed at the MoO x/n-Si boundary zone without preoxidation and is of amorphous structure, which is determined by a high-resolution transmission electron microscope with energy-dispersive X-ray spectroscopy mapping. The creation of lower-oxidation states in MoO x film indicates that the gradient distribution of SiO x with Mo element occurs within the interlayer, acting as a passivation of silicon substrate, which is revealed by X-ray photoelectron spectroscopy with depth etching. Specifically, calculations by density functional theory manifest that there are two half-filled levels (localized states) and three unoccupied levels (extended states) relating to Mo component in the ternary hybrid a-SiO x(Mo) interlayer, which play the roles of defect-assisted tunneling and direct tunneling for photogenerated holes, respectively. The transport process of photogenerated holes in the MoO x/n-Si heterojunction device is well-described by the tunnel-recombination model. Meanwhile, the a-SiO x/poly(Si(n+)) has been assembled on the rear of the device for direct tunneling of photoinduced electrons and blocking photoinduced holes.

Doping ZnO Electron Transport Layers with MoS2 Nanosheets Enhances the Efficiency of Polymer Solar Cells.

In this study, we incorporated molybdenum disulfide (MoS2) nanosheets into sol-gel processing of zinc oxide (ZnO) to form ZnO:MoS2 composites for use as electron transport layers (ETLs) in inverted polymer solar cells featuring a binary bulk heterojunction active layer. We could effectively tune the energy band of the ZnO:MoS2 composite film from 4.45 to 4.22 eV by varying the content of MoS2 up to 0.5 wt %, such that the composite was suitable for use in bulk heterojunction photovoltaic devices based on poly[bis(5-(2-ethylhexyl)thien-2-yl)benzodithiophene- alt-(4-(2-ethylhexyl)-3-fluorothienothiophene)-2-carboxylate-2,6-diyl] (PTB7-TH)/phenyl-C71-butryric acid methyl ester (PC71BM). In particular, the power conversion efficiency (PCE) of the PTB7-TH/PC71BM (1:1.5, w/w) device incorporating the ZnO:MoS2 (0.5 wt %) composite layer as the ETL was 10.1%, up from 8.8% for the corresponding device featuring ZnO alone as the ETL, a relative increase of 15%. Incorporating a small amount of MoS2 nanosheets into the ETL altered the morphology of the ETL and resulted in enhanced current densities, fill factors, and PCEs for the devices. We used ultraviolet photoelectron spectroscopy, synchrotron grazing incidence wide-/small-angle X-ray scattering, atomic force microscopy, and transmission electron microscopy to characterize the energy band structures, internal structures, surface roughness, and morphologies, respectively, of the ZnO:MoS2 composite films.

Direct Photolithography on Molecular Crystals for High Performance Organic Optoelectronic Devices.

Organic crystals are generated via the bottom-up self-assembly of molecular building blocks which are held together through weak noncovalent interactions. Although they revealed extraordinary charge transport characteristics, their labile nature represents a major drawback toward their integration in optoelectronic devices when the use of sophisticated patterning techniques is required. Here we have devised a radically new method to enable the use of photolithography directly on molecular crystals, with a spatial resolution below 300 nm, thereby allowing the precise wiring up of multiple crystals on demand. Two archetypal organic crystals, i.e., p-type 2,7-diphenyl[1]benzothieno[3,2- b][1]benzothiophene (Dph-BTBT) nanoflakes and n-type N, N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) nanowires, have been exploited as active materials to realize high-performance top-contact organic field-effect transistors (OFETs), inverter and p-n heterojunction photovoltaic devices supported on plastic substrate. The compatibility of our direct photolithography technique with organic molecular crystals is key for exploiting the full potential of organic electronics for sophisticated large-area devices and logic circuitries, thus paving the way toward novel applications in plastic (opto)electronics.

The fabrication of Cd-free Cu2ZnSnS4-Ag2ZnSnS4 heterojunction photovoltaic devices

Cu2ZnSnS4 (CZTS) is a low cost, non-toxic material composed of earth-abundant elements with a large optical absorption coefficient. However, in CZTS solar cells, CdS buffer layers are widely used, which contain toxic elements and lead to lattice mismatch with CZTS thin films. In this paper, we have systematically investigated a I-II-IV-VI semiconductor material to replace the CdS buffer layer with a non-toxic material that offers good lattice matching with the CZTS film. For the first time, Cd-free Cu2ZnSnS4-Ag2ZnSnS4 heterojunction photovoltaic device is fabricated, where Cu2ZnSnS4 and Ag2ZnSnS4 layers are obtained by co-sputtering method. The cell exhibits a 4.51% efficiency which is higher than those of CZTS solar cells with ZnS and In2S3 buffer layers. This work offers the possibility to realize environmentally benign, scalable, low-cost, and high-efficiency solar cells.

Hue tunable, high color saturation and high-efficiency graphene/silicon heterojunction solar cells with MgF2/ZnS double anti-reflection layer

Graphene/silicon (Gr/Si) heterojunctions with simple manufacturing process, high stability and excellent device performance have great potential in photovoltaic (PV) applications. In comparison to conventional PV panels with monotone colors, multi-color PV panels could be integrated in modern building facades and thus largely expand their application ranges. In this work, multi-color Gr/Si heterojunction PV devices were fabricated, for the first time, by taking advantage of the combination of ultra-thin highly transparent graphene and MgF2/ZnS anti-reflection coating. The double-layer film coating enabled the multi-color Gr/Si PV devices with both high color saturation and low optical loss. The PV devices exhibited respectable power conversion efficiency (PCE) in the range of 10.7–13.2%, depending on the color of the devices. In addition, PCE of the device with optimized anti-reflection coating reached as high as 14.6%, which is among the highest for the Gr/Si heterojunction solar cells. By varying the film thickness at different positions, a colored Gr/Si solar cell with visible pattern was made on a 2-in. Si wafer. Our work demonstrates the great potential of multi-colored Gr/Si solar cells for new-generation distributed solar energy systems with designable features.

Vertically aligned CdTe nanorods array for novel three-dimensional heterojunction solar cells on Ni substrates

In this study, a uniform CdTe nanorods (NRs) arrays are grown on Ni substrates by a simple one-step electrochemical deposition method. The effects of deposition parameters such as the concentration of reactants and reaction time on the growth of CdTe NRs arrays are systematically investigated. Na2TeO3 and CdSO4 have a significantly different influence on the growth of CdTe NRs. With the increase of Na2TeO3 concentration, the diffraction intensity increases slightly at the peak (111) to promote axial growth. The diffraction intensity of (002) can increase with the concentration of CdSO4 increasing, which is conducive to lateral growth. The morphology of CdTe film varies from a thin layer to nanoparticles, and finally to NRs with the extension of time. Based on the characterization results, the possible growth mechanism of CdTe NRs arrays is proposed. The as-prepared CdTe NRs arrays are then embedded into CdS film, forming a novel three-dimensional (3D) heterojunction photovoltaic device. An extensive study of the effect of NRs length on device performance is presented. The results indicate that the device performance is highly dependent on the length of CdTe NRs, and a power conversion efficiency of 2.50% is obtained for optimal length of 1 μm. The better photovoltaic performance can be attributed to its efficient charge separation and direct pathways for carriers transport. What's more, this novel 3D nanostructured concept suggests great potential for other optoelectronic devices.

Fabrication and study of sol-gel ZnO films for use in Si-based heterojunction photovoltaic devices

This paper considers the use of zinc oxide thin films prepared via the sol-gel route as an n-type layer in heterojunction ZnO/Si solar cells. The ZnO films were prepared via a simple spin-coating technique using zinc acetate dihydrate as a zinc precursor, isopropanol as a solvent and monoethanolamine as a stabilizing agent. Optical, structural and morphological properties of ZnO were investigated for thin films grown from sol-gel solutions with different concentrations both on glass and silicon substrates. As such, a distribution of crystallite sizes and surface topology parameters corresponding to various zinc acetate dihydrate concentrations were obtained to elucidate optimal film deposition conditions. Correlation between thin film morphology and structural characteristics of ZnO thin films was made based on atomic-force microscopy studies. Finally, our results on fabrication, characterization and simulation of ZnO/Si heterojunctions for use as photovoltaic devices are presented. Although noticeable rectifying and photovoltaic properties were observed for Al/Si/ZnO/Ti/Au devices, there appears to exist a considerable room for device improvement with simulation studies suggesting that efficiencies of the order of 24% may be obtained for devices with optimal silicon wafer passivation, i.e. with lifetimes of the order of 1000 μs.

High Performance PbS Colloidal Quantum Dot Solar Cells by Employing Solution‐Processed CdS Thin Films from a Single‐Source Precursor as the Electron Transport Layer

AbstractCdS thin films are a promising electron transport layer in PbS colloidal quantum dot (CQD) photovoltaic devices. Some traditional deposition techniques, such as chemical bath deposition and RF (radio frequency) magnetron sputtering, have been employed to fabricate CdS films and CdS/PbS CQD heterojunction photovoltaic devices. However, their power conversion efficiencies (PCEs) are moderate compared with ZnO/PbS and TiO2/PbS heterojunction CQD solar cells. Here, efficiencies have been improved substantially by employing solution‐processed CdS thin films from a single‐source precursor. The CdS film is deposited by a straightforward spin‐coating and annealing process, which is a simple, low‐cost, and high‐material‐usage fabrication process compared to chemical bath deposition and RF magnetron sputtering. The best CdS/PbS CQD heterojunction solar cell is fabricated using an optimized deposition and air‐annealing process achieved over 8% PCE, demonstrating the great potential of CdS thin films fabricated by the single‐source precursor for PbS CQDs solar cells.

Interface Electrode Morphology Effect on Carrier Concentration and Trap Defect Density in an Organic Photovoltaic Device.

Formation of Schottky barrier contact (SBC) leads reconstruction of charges at the metal/semiconductor (MS) interface because of the wave function overlap between semiconductor and metal contact. Not only is the Schottky barrier contact formation a signature of the material's work function, but also it is sensitive to the interface trap states, the crystal orientation of the interacting materials, and other interface properties. In this work, the effect of aluminum cathode morphology on the polymer Schottky diode and bulk heterojunction (BHJ) photovoltaic device performance is studied. The electron collecting contacts in Schottky diode and BHJ device have been deposited using aluminum in pellet and nanoparticle forms. Devices fabricated by using Al nanoparticle showed improvement in dark as well as photocurrent density. Significant enhancement in JSC leads to overall improved power conversion efficiency. Enhanced performance in Schottky structured diode and OPV device have been correlated with electrode microstructure and its interface properties such as improved electrically active contact and enhanced charge transport. Electrical conductivity is discussed based on enhanced electrical coherence across organic semiconductor and electrode interface. Therefore, the contribution of electrical enhancement leads to improvement in short-circuit current density (JSC) in BHJ solar cell which is due to reduced trap density. Further, PCE was correlated with the density of interface trap states studied by drive level capacitance profiling technique.

Decakis(arylthio)corannulenes: Transferable Photochemical and Redox Parameters and Photovoltaic Device Performance

Absorption and redox properties of seven decakis(phenylthio)corannulene derivatives 3a–3g lead to a model for estimating material properties in persulfurated aromatic compounds. The same series is evaluated for performance in bulk heterojunction and perovskite photovoltaic devices.

Photovoltaic device performance of highly regioregular fluorinated poly(3-hexylthiophene)

Abstract Highly regioregular poly(3-hexylthiophene) derivatives with varying degrees of fluorine substitution on the thiophene moieties have been demonstrated in photovoltaic devices and characterized using ultraviolet and inverse photoelectron spectroscopy. As fluorine content is increased, an increase in ionization energy of 0.3 eV is observed for 50% fluorination compared to non-fluorinated poly(3-hexylthiophene). The electron affinity is observed to increase to a lesser extent with increased fluorination, consistent with a systematic increase in the optical bandgaps of up to 0.12 eV. Bulk heterojunction photovoltaic devices made from polymer:PC 61 BM blends achieve power conversion efficiencies of 3%, however film morphologies measured using atomic force microscopy indicate that strong phase separation with increasing fluorination limits device performance. UV–vis spectra of thin films of the fluorinated materials exhibit a long tail in the red, extending to longer wavelengths than non-fluorinated poly(3-hexylthiophene). Photovoltaic devices similarly exhibit non-zero quantum efficiency in this region. This behavior has been attributed to a low energy, interchain charge transfer state.

A theoretical investigation of the structural, electronic and UV–vis absorption spectra of fullerene derivatives based on PC61B-NHCS compound

Fullerene derivatives, as novel acceptors, have been successfully applied in bulk heterojunction (BHJ) photovoltaic devices. A new fullerene derivative, PC61B-NHCS, has been recently synthesized as an electron acceptor for improving absorption and power conversion efficiency (PCE) by modifying [C60]-PCBM. In this work, we analyze the structural and electronic properties of PC61B-NHCS using density functional theory (DFT) calculations by employing a hybrid B3LYP-D3 level of theory. Also, we study the UV–Vis absorption spectrum of this compound using time-dependent DFT (TD-DFT) method. The calculated results of energy levels and oscillator strengths are consistent with the available experimental data. Furthermore, we have investigated substituents effect on the LUMO levels and absorption spectra in designing the new acceptors. The results reveal that the methyl group on the para-position of the phenyl ring improves the electrical and optical properties of the complex under evaluation. The strong absorption in the visible region and an increase in the LUMO level of the presented complex can enhance the Jsc and Voc values of BHJ photovoltaic devices and therefore maximize the efficiency of BHJ photovoltaic devices. We hope our studies in the present work can offer a theoretical guideline in designing the fullerene-based acceptors for organic solar cells.

Naphthalene Diimide-Based n-Type Polymers: Efficient Rear Interlayers for High-Performance Silicon-Organic Heterojunction Solar Cells.

Silicon-organic heterojunction solar cells suffer from a noticeable weakness of inefficient rear contact. To improve this rear contact quality, here, two solution-processed organic n-type donor-acceptor naphthalene diimide (NDI)-based conjugated polymers of N2200 and fluorinated analogue F-N2200 are explored to reduce the contact resistance as well as to passivate the Si surface. Both N2200 and F-N2200 exhibit high electron mobility due to their planar structure and strong intermolecular stacking, thus allowing them to act as excellent transporting layers. Preferential orientation of the polymers leads to reduce contact resistance between Si and cathode aluminum, which can enhance electron extraction. More importantly, the substitution of fluorine atoms for hydrogen atoms within the conjugated polymer can strengthen the intermolecular stacking and improve the polymer-Si electronic contact due to the existence of F···H interactions. The power conversion efficiencies of Si-PEDOT:PSS solar cells increased from 12.6 to 14.5% as a consequence of incorporating the F-N2200 polymer interlayers. Subsequently, in-depth density functional theory simulations confirm that the polymer orientation plays a critical role on the polymer-Si contact quality. The success of NDI-based polymers indicates that planar conjugated polymer with a preferred orientation could be useful in developing high-performance solution-processed Si-organic heterojunction photovoltaic devices.

Effective Passivation and Tunneling Hybrid a-SiOx(In) Layer in ITO/n-Si Heterojunction Photovoltaic Device.

In this article, using controllable magnetron sputtering of indium tin oxide (ITO) materials on single crystal silicon at 100 °C, the optoelectronic heterojunction frame of ITO/a-SiOx(In)/n-Si is simply fabricated for the purpose of realizing passivation contact and hole tunneling. It is found that the gradation profile of indium (In) element together with silicon oxide (SiOx/In) within the ultrathin boundary zone between ITO and n-Si occurs and is characterized by X-ray photoelectron spectroscopy with the ion milling technique. The atomistic morphology and physical phase of the interfacial layer has been observed with a high-resolution transmission electron microscope. X-ray diffraction, Hall effect measurement, and optical transmittance with Tauc plot have been applied to the microstructure and property analyses of ITO thin films, respectively. The polycrystalline and amorphous phases have been verified for ITO films and SiOx(In) hybrid layer, respectively. For the quantum transport, both direct and defect-assisted tunneling of photogenerated holes through the a-SiOx(In) layer is confirmed. Besides, there is a gap state correlative to the indium composition and located at Ev + 4.60 eV in the ternary hybrid a-SiOx(In) layer that is predicted by density functional theory of first-principles calculation, which acts as an "extended delocalized state" for direct tunneling of the photogenerated holes. The reasonable built-in potential (Vbi = 0.66 V) and optimally controlled ternary hybrid a-SiOx(In) layer (about 1.4 nm) result in that the device exhibits excellent PV performance, with an open-circuit voltage of 0.540 V, a short-circuit current density of 30.5 mA/cm2, a high fill factor of 74.2%, and a conversion efficiency of 12.2%, under the AM 1.5 illumination. The work function difference between ITO (5.06 eV) and n-Si (4.31 eV) is determined by ultraviolet photoemission spectroscopy and ascribed to the essence of the built-in-field of the PV device. In addition, the strong inversion layer in the surface of the n-Si substrate is tentatively correlated to the a-SiOx(In) interface layer as well.

Electrochemical Synthesis of Films Based on Polybithiophene and Fullerene Derivatives with Potential Use in Bulk Heterojunction Photovoltaic Devices

Two electrochemical methods, cyclic voltammetry and constant potential, were used for the electrodeposition of redox active composite film containing polybithiophene-fullerene (E-(pBTh/C60 derivative)) and fullerene derivatives (PC60BM and IC60BA) on ITO substrates. Preparation was carried out in one step synthesis directly from a solution containing the monomer and the fullerene derivative. The incorporation of the fullerene compound was characterized by UV-Vis and NIR, as well as conductance measurements. The prepared thin films were also electrochemically analyzed, determining that those generated by cyclic voltammetry have slightly greater reversibility: (Qa/Qc > 80% after 50 cycles of charge-discharge). Morphological analysis (AFM) showed that voltammetric deposition generates rougher and thicker films (roughness greater than 100 nm and thickness higher than 200 nm) than constant potential films, whose roughness is in the range from 20 to 60 nm and the thickness is 150 nm. For these reasons, films prepared by constant potential were used for manufacturing the active layer of a simple photovoltaic device Glass/ITO/E-(pBTh:PC60BM)/Field’s metal, which showed charge separation with Voc of 0.28 V and Jsc of 42 μA/cm2 respectively.

Controlled Addition of Carbon Nanotube Defects and Their Role in Limiting Solar Cell Performance

Semiconducting single-walled carbon nanotubes (s-SWCNTs) have attracted significant attention as a photoactive component in thin film photovoltaics due to their strong absorptivity and high charge mobility. However, the external quantum efficiency (EQE) of s-SWCNT/C60 heterojunction solar cells is limited by poor exciton diffusion to the heterointerface. Exciton diffusion is believed to be strongly dependent on the length between defects, which quench excitons. Here, we systematically study the influence of defects on s-SWCNT/C60 planar heterojunction photovoltaic devices. We use covalent sidewall functionalization via diazonium chemistry to introduce sp3 defects to the s-SWCNTs at varying concentrations. We generate a defect-adding model to describe the position of defects on the surface of the nanotube, and use it to successfully reproduce the time-resolved exciton decay rate measured with transient absorption spectroscopy. We fabricate s-SWCNT/C60 heterojunction photovoltaic cells and characterize the EQE as a function of defect concentration. We develop a diffusion limited contact quenching Monte Carlo model to reproduce the EQE trends we observe. The model allows us to predict the behavior of theoretical s-SWCNT devices with varying length distribution and defect concentration, toward the limit of long length and zero defects. This work guides the field of nanotube photovoltaics and illuminates the promise and limitations of s-SWCNT solar cell devices.

Role of Defects as Exciton Quenching Sites in Carbon Nanotube Photovoltaics

Semiconducting single-walled carbon nanotubes (s-SWCNTs) have attracted significant attention as a photoactive component in thin film photovoltaic solar cells and photodetectors due to their strong optical absorptivity and high charge transport mobility. However, the external quantum efficiency (QE) of s-SWCNT/acceptor heterojunction solar cells has been limited by poor exciton harvesting efficiency. Exciton trapping and quenching at defects are a suspected source of loss. Here, we study the influence of defects on bilayer s-SWCNT/C60 planar heterojunction photovoltaic devices via both experiment and modeling. First, diazonium chemistry is used to introduce covalent sp3 sidewall defects to s-SWCNTs at various densities that are estimated using Raman and transient absorption spectroscopy. s-SWCNT/C60 heterojunction photovoltaic cells are then fabricated that show a significant decrease in peak external QE (e.g., from 40% to 8%) with increasing defect density. Second, a diffusion-limited contact quenching M...

Ag-Incorporated Organic-Inorganic Perovskite Films and Planar Heterojunction Solar Cells.

Controlled doping for adjustable material polarity and charge carrier concentration is the basis of semiconductor materials and devices, and it is much more difficult to achieve in ionic semiconductors (e.g., ZnO and GaN) than in covalent semiconductors (e.g., Si and Ge), due to the high intrinsic defect density in ionic semiconductors. The organic-inorganic perovskite material, which is frenetically being researched for applications in solar cells and beyond, is also an ionic semiconductor. Here we present the Ag-incorporated organic-inorganic perovskite films and planar heterojunction solar cells. Partial substitution of Pb2+ by Ag+ leads to improved film morphology, crystallinity, and carrier dynamics as well as shifted Fermi level and reduced electron concentration. Consequently, in planar heterojunction photovoltaic devices with inverted stacking structure, Ag incorporation results in an enhancement of the power conversion efficiency from 16.0% to 18.4% in MAPbI3 based devices and from 11.2% to 15.4% in MAPbI3-xClx based devices. Our work implies that Ag incorporation is a feasible route to adjust carrier concentrations in solution-processed perovskite materials in spite of the high concentration of intrinsic defects.