Quantum Efficiency Curves Research Articles

A Terminally Tetrafluorinated Nonfullerene Acceptor for Well‐Performing Alloy Ternary Solar Cells

AbstractFabricating ternary solar cells is a pivotal strategy to improve the power conversion efficiencies (PCEs) of organic photovoltaic devices. However, it is still a challenge to simultaneously improve the performance parameters of ternary devices. Therefore, the third ingredient in ternary blends should be precisely designed or selected. Herein, a new medium‐bandgap small‐molecule acceptor, namely, 3,9‐bis(2‐methylene‐(3‐(1‐(3,5‐dimethylphenyl)‐1cyanomethylene)indanone))‐5,5,11,11‐tetrakis‐(4‐hexylphenyl)dithieno[2,3‐d:2′,3′‐d′]‐sindaceno[1,2‐b:5,6‐b′]dithiophene (ITIF), is synthesized by end‐capping with a new fluorinated, asymmetric terminal group, (Z)‐2‐(3,5‐difluorophenyl)‐2‐(3‐oxo‐2,3‐dihydro‐1H‐inden‐1‐ylidene) acetonitrile. Replacing the CN substituent with the asymmetric 3,5‐difluorophenyl substituent obviously up‐shifts the lowest unoccupied molecular orbital (LUMO) level of ITIF to −3.78 eV, enlarges the bandgap to 1.82 eV, and improves the absorption coefficient to ≈50% higher than that of 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)indanone))‐5,5,11,11‐tetrakis‐(4‐hexylphenyl)dithieno[2,3‐d:2′,3′‐d′]‐sindaceno[1,2‐b:5,6‐b′]dithiophene (ITIC). Due to the similar structures, ITIF and ITIC can combine as an alloyed acceptor, which makes it convenient to tune the morphology and optical and electrochemical properties of ternary blends. The enhanced absorption coefficient of ITIF and the rapid fluorescence resonance energy transfer from ITIF to ITIC remarkably improve the absorption of the ternary blend film, hence compensating for the external quantum efficiency (EQE) curves. When ITIF is introduced into ternary solar cells based on poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione)] (PBDB‐T):ITIF:ITIC blends, the PCEs of the ternary devices are increased from 9.2% to 10.5%, and the short‐circuit currents, open‐circuit voltages, and fill factors are simultaneously improved.

Fluorobenzotriazole (FTAZ)‐Based Polymer Donor Enables Organic Solar Cells Exceeding 12% Efficiency

AbstractThe fluorobenzotriazole (FTAZ)‐based copolymer donors are promising candidates for nonfullerene polymer solar cells (PSCs), but suffer from relatively low photovoltaic performance due to their unsuitable energy levels and unfavorable morphology. Herein, three polymer donors, L24, L68, and L810, based on a chlorinated‐thienyl benzodithiophene (BDT‐2Cl) unit and FTAZ with different branched alkyl side chain, are synthesized. Incorporation of a chlorine (Cl) atom into the BDT unit is found to distinctly optimize the molecular planarity, energy levels, and improve the polymerization activity. Impressively, subtle side chain length of FTAZ realizes a dramatic improvement in all the device parameters, as revealed by the short‐current density (Jsc) improved from 7.41 to 20.76 mA cm−2, fill‐factor from 36.3 to 73.5%, and even the open‐circuit voltage (Voc) from 0.495 to 0.790 V. The best power conversion efficiency (PCE) of 12.1% is obtained from the L810‐based device, which is one of the highest values reported for FTAZ‐based PSCs so far. Notably, the corresponding external quantum efficiency curve keeps a very prominent value up to 80% from 500 to 800 nm. The notable performance is discovered from the reduced energy loss, improved molecular face‐on orientation, the down‐shifted energy levels, and optimized absorption coefficient regulated by side‐chain engineering.

Proton-Induced Scintillation Properties of a UV-Cured Plastic Scintillator

In this study, we fabricated and characterized a UV-curable plastic scintillation resin for 3D printing technology. The resin for 3D printing was prepared by using the co-polymers MMA (methyl meta-acrylate, DHPA (dipentaerythritol hexa-acrylate), naphthalene and PPO (2,5- diphenyloxazole) organic scintillator obtained from Sigma Aldrich. Irgacure 184 (BASF Co.) was used as a photo-initiator. Protons and X-ray-induced luminescence spectra of the UV-cured plastic scintillator were measured. For the emission spectrum, QE65000 and USB4000 optic spectrometers (Ocean Optics) were used. The cured plastic scintillator showed an emission spectrum at wavelength between 380 and 650 nm, peaking at 405 nm and 550 nm, excited by using 100 MeV proton. The observed emission matched well with the quantum efficiency curve of the photodiode. The result showed that the scintillator provided the possibility of adding 3D printing technology, and applications can be found in human dosimetry, etc.

Performance enhancement of flexible CZTSSe solar cells on optimized roughness substrate

Flexible Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells are fabricated on titanium substrate by magnetron sputtering with a composition gradient precursor followed by selenization. By varying polishing time with diluted HNO3 and HF from 0 to 90 s, an atomic force microscope shows that the substrate with the minimal surface roughness of 8.6 nm is obtained with the polishing time of 60 s. X-ray diffraction and Raman spectroscopy reveal a highly crystalline structure for the prepared CZTSSe thin films. The gradual grown up grain size of CZTSSe thin film is observed with the increasing polishing time of the substrate. Compared with the CZTSSe solar cells on untreated titanium substrates, a maximum power conversion efficiency enhancement of 56% is achieved for solar cells on polished substrates, which can be attributed to the reduction of recombination at the interface and isolated defects in devices. External quantum efficiency curves show an enhancement in the visible and near-infrared region after optimizing substrate roughness. On the basis of Ti substrate with a minimum roughness, the percentage reduction of efficiency is found to exhibit the minimum value of 5% after bending for five times.

Bulk heterojunction photovoltaics with improved efficiencies using stem-leaf, shish-kebab and double-fibrillar nano-hybrids based on modified carbon nanotubes and poly(3-hexylthiophene)

For improving the photovoltaic efficiencies, the conductive ordered and disordered nano-hybrids were developed as morphology mediator based on multi-walled carbon nanotubes (CNTs), their chemically surface modified derivatives, regioregular poly(3-hexyl thiophene) (RR-P3HT) and non-regioregular poly(3-dodecyl thiophene) (PDDT). In unmodified CNTs and their derivatives functionalized with 2-hydroxymethyl thiophene (CNT-f-COOTh, FCNT) and grafted with poly(3-dodecylthiophene) (CNT-g-PDDT, GCNT), double-fibrillar, shish-kebab, and stem-leaf nanostructures were decorated. When the pre-developed FCNT/P3HT and GCNT/P3HT nano-hybrids were applied in thin active layers, a progress was detected in photovoltaic characteristics, in particular for P3HT:GCNT/P3HT devices via larger phase separations. The current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) values ranged in 8.14–8.66 mA/cm2, 49–51%, and 2.55–2.78% for P3HT:GCNT/P3HT systems, respectively. The best photovoltaic features were detected for P3HT:GCNT/P3HT:phenyl-C71-butyric acid methyl ester (PC71BM) devices (Jsc = 9.91–10.22 mA/cm2, FF = 57–59%, and PCE = 3.50–3.74%). The peak values around 69–71% and 52–54% in the external quantum efficiency (EQE) curves were detected at about 550 nm for P3HT:GCNT/P3HT:PCBM and P3HT:GCNT/P3HT devices, respectively.

Two-dimensional simulation of GaAsSb/GaAs quantum dot solar cells

Two-dimensional (2D) simulation of GaAsSb/GaAs quantum dot (QD) solar cells is presented. The effects of As mole fraction in GaAsSb QDs on the performance of the solar cell are investigated. The solar cell is designed as a p-i-n GaAs structure where a single layer of GaAsSb QDs is introduced into the intrinsic region. The current density–voltage characteristics of QD solar cells are derived from Poisson’s equation, continuity equations, and the drift-diffusion transport equations, which are numerically solved by a finite element method. Furthermore, the transition energy of a single GaAsSb QD and its corresponding wavelength for each As mole fraction are calculated by a six-band k · p model to validate the position of the absorption edge in the external quantum efficiency curve. A GaAsSb/GaAs QD solar cell with an As mole fraction of 0.4 provides the best power conversion efficiency. The overlap between electron and hole wave functions becomes larger as the As mole fraction increases, leading to a higher optical absorption probability which is confirmed by the enhanced photogeneration rates within and around the QDs. However, further increasing the As mole fraction results in a reduction in the efficiency because the absorption edge moves towards shorter wavelengths, lowering the short-circuit current density. The influences of the QD size and density on the efficiency are also examined. For the GaAsSb/GaAs QD solar cell with an As mole fraction of 0.4, the efficiency can be improved to 26.2% by utilizing the optimum QD size and density. A decrease in the efficiency is observed at high QD densities, which is attributed to the increased carrier recombination and strain-modified band structures affecting the absorption edges.

Numerical analysis and optimization of Cu2O/TiO2, CuO/TiO2, heterojunction solar cells using SCAPS

In the presented work, the Cu2O/TiO2 and CuO/TiO2 heterojunction solar cells have been analyzed by the help of Solar Cell Capacitance Simulator (SCAPS). The effects of various layer parameters like thickness and defect density on the cell performance have been studied in details. Numerical analysis showed how the absorber (CuO, Cu2O) and buffer (TiO2) layers thickness influence the short-circuit current density (Jsc) and efficiency (η) of solar cells. Optimized solar cell structures of Cu2O/TiO2 and CuO/TiO2 showed a potential efficiency of ∼9 and ∼23%, respectively, under the AM1.5G spectrum. Additionally, external quantum efficiency (EQE) curves of the CuO/TiO2 and Cu2O/TiO2 solar cells for various layers thickness of TiO2 were calculated and the optical band gap (Eg) for CuO and Cu2O was obtained. Finally, we examined the effects of defect density on the photovoltaic parameters.

Existence of multiple phases and defect states of SnS absorber and its detrimental effect on efficiency of SnS solar cell

Tin sulfide (SnS) film is grown by sputtering process with subsequent post-sulfurization. As-deposited SnS consists of orthorhombic and cubic structure SnS whereas post-sulfurized films showed pure orthorhombic crystal structure. This structural transformation was confirmed by X-ray diffraction (XRD), Raman spectroscopy and UV–Vis spectroscopy. We used post-annealed SnS film as an absorber layer of solar cell. The fabricated SnS solar cell was composed of SLG/Mo/SnS/CdS/i-ZnO/ITO. We measured current density-voltage (J-V) and external quantum efficiency (EQE) curves for the completed devices. The best efficiency of SnS solar cell was ∼0.5%. The EQE curve showed existence of multiple phases of SnS, even though XRD and Raman spectroscopy showed pure SnS phase. The multiple phases were observed again by photoluminescence (PL). PL also revealed deep defect states of SnS absorber. Thus, the inhomogeneous SnS absorber is one of the main bottlenecks for high efficiency SnS solar cell.

Influence of interface layer preparation on the electrical and spectral characteristics of GaN/Si solar cells

Volt-ampere and spectral characteristics of GaN/Si solar cell samples differing in interface layer preparation are obtained and analyzed. External quantum efficiency curves are experimentally determined via excitation with a 532 nm incident radiation wavelength. It is demonstrated that interface preparation has a significant influence on photovoltaic characteristics of the studied samples.

High Performance Silicon/Organic Hybrid Solar Cells with Dual Localized Surface Plasmonic Effects of Ag and Au Nanoparticles

Effective light trapping induced by a dual localized plasmonic effect of Au and Ag nanoparticles (NPs) is adopted in poly‐(3,4‐ethylenedioxythiophene):poly (styrenesulfonic acid) (PEDOT:PSS) hybrid solar cells. Superior performance on light absorption is obtained after incorporating mixed Au and Ag NPs incorporating into PEDOT:PSS layer. Compared to devices with single NPs that only shows very limited plasmonic enhancement, dual NPs doped devices benefit from the dual plasmonic enhancement in visible light region. Therefore, power conversion efficiency (PCE) of 11.98 % has been achieved, which is about 18% higher than that of with the pristine one, exhibiting a PCE of 9.72%. The PCE enhancement is largely ascribed to the short‐circuit current (JSC) enhancement, which can be observed through the external quantum efficiency (EQE) curves. In addition, transient photovoltage (TPV) results show that the charge carrier lifetime is improved by the incorporation of dual nanoparticles, indicating a suppressed charge recombination during the physical process in the devices.

Efficient design of perovskite solar cell using mixed halide and copper oxide

Solar cells based on perovskites have emerged as a transpiring technology in the field of photovoltaic. These cells exhibit high power conversion efficiency. The perovskite material is observed to have good absorption in the entire visible spectrum which can be well illustrated by the quantum efficiency curve. In this paper, theoretical analysis has been done through device simulation for designing solar cell based on mixed halide perovskite. Various parameters have efficacy on the solar cell efficiency such as defect density, layer thickness, doping concentration, band offsets, etc. The use of copper oxide as the hole transport material has been analyzed. The analysis divulges that due to its mobility of charge carriers, it can be used as an alternative to spiro-OMeTAD. With the help of simulations, reasonable materials have been employed for the optimal design of solar cell based on perovskite material. With the integration of copper oxide into the solar cell structure, the results obtained are competent enough. The simulations have shown that with the use of copper oxide as hole transport material with mixed halide perovskite as absorber, the power conversion efficiency has improved by 6%. The open circuit voltage has shown an increase of 0.09 V, short circuit current density has increased by 2.32 mA/cm2, and improvement in fill factor is 8.75%.

Comparative study on the influence of Al component at GaAlAs layer for GaAs/AlGaAs photocathode**Project supported by the National Natural Science Foundation of China (Nos. 91433108, 61301023).

We designed two transmission-mode GaAs/AlGaAs photocathodes with different AlxGa1−x As layers, one has an AlxGa1−xAs layer with the Al component ranging from 0.9 to 0, and the other has a fixed Al component 0.7. Using the first-principle method, we calculated the electronic structure and absorption spectrum of AlxGa1−xAs at x = 0, 0.25, 0.5, 0.75 and 1, calculation results suggest that with the increase of the Al component, the band gap of AlxGa1−xAs increases. Then we activated the two samples, and obtained the spectral response curves and quantum efficiency curves; it is found that sample 1 has a better shortwave response and higher quantum efficiency at short wavelengths. Combined with the band structure diagram of the transmission-mode GaAs/AlGaAs photocathode and the fitted performance parameters, we analyze the phenomenon. It is found that the transmission-mode GaAs/AlGaAs photocathode with variable Al component and various doping structure can form a two-stage built-in electric field, which improves the probability of shortwave response photoelectrons escaping to the vacuum. In conclusion, such a structure reduces the influence of back-interface recombination, improves the shortwave response of the transmission-mode photocathode.

Synthesis and Characterization of SnO2 on Porous Silicon for Photoconversion

A photoconversion device was fabricated based on SnO2 film prepared by a chemical spray pyrolysis technique. The SnO2 nanofilms were grown on the porous silicon (PS) nanosurface. Various affecting parameters were studied such as different current densities 20, 30, 40, 50 and 60 mA/cm2 with 16% HF concentration for 10 min at a substrate temperature of 400 °C. The structural, morphological and detector properties were measured. X-ray diffraction (XRD) confirmed the formation of porous silicon and the crystal size was reduced toward the nanometric scale of the face centered cubic structure, while the diffraction peaks of other SnO2 peaks were found to be much weaker compared to standard SnO2NPs. The Atomic Force Microscope (AFM) investigation showed the sponge-like structure of PS, the width of surface pits and surface roughness increased to a specific value then decreased with etching current density. This could be attributed to the different filling process depending on the pore sizes and homogenous distribution of PS. From the found photodetector measurements, the spectral responsivity and quantum efficiency curves included two regions; the first region was due to the absorption of UV light by SnO2NPs. The second region corresponded to the visible light absorption with the PS layer and strongly depended on fabrication conditions.

Comparative research on the influence of varied Al component on the active layer of AlGaN photocathode**Project supported by the National Natural Science Foundation of China (Nos. 61308089, 6144005) and the Public Technology Applied Research Project of Zhejiang Province (No. 2013C31068).

To theoretically research the influence of a varied Al component on the active layer of AlGaN photocathodes, the first principle based on density functional theory is used to calculate the formation energy and band structure of AlxGa1−xN with x at 0, 0.125, 0.25, 0.325, and 0.5. The calculation results show that the formation energy declines along with the Al component rise, while the band gap is increasing with Al component increasing. AlxGa1−xN with x at 0, 0.125, 0.25, 0.325, and 0.5 are direct band gap semiconductors, and their absorption coefficient curves have the same variation tendency. For further study, we designed two kinds of reflection-mode AlGaN photocathode samples. Sample 1 has an AlxGa1−xN active layer with varied Al component ranging from 0.5 to 0 and decreasing from the bulk to the surface, while sample 2 has an AlxGa1−xN active layer with the fixed Al component of 0.25. Using the multi-information measurement system, we measured the spectral response of the activated samples at room temperature. Their photocathode parameters were obtained by fitting quantum efficiency curves. Results show that sample 1 has a better spectral response than sample 2 at the range of short-wavelength. This work provides a reference for the structure design of the AlGaN photocathode.

Surface chemical cleaning of the extended blue varied-doping Ga0.37Al0.63As photocathode

To improve the quantum efficiency of the extended blue varied-doping Ga0.37Al0.63As photocathode, different cleaning methods for oxide and carbon on the surface of the Ga0.37Al0.63As photocathode were investigated. The surface structure and atomic compositions of the Ga0.37Al0.63As photocathode were measured by X-ray photoelectron spectroscopy and Ar+ ion sputtering. After preparation and activation of the Ga0.37Al0.63As photocathode in an ultra-high vacuum system, the spectral response curves and quantum efficiency curves were measured, and then, curve fitting and analysis were performed. The experimental results showed that in regard to surface chemical cleaning of the Ga0.37Al0.63As samples, it was difficult to effectively remove the oxide with only the H2SO4:H2O2:H2O (4:1:100) solution, while carbon could not be removed with the HCl:H2O (1:3) solution alone. A two-step chemical cleaning method with the H2SO4:H2O2:H2O (4:1:100) solution and HCl:H2O (1:3) solution could effectively remove the oxide as well as the carbon. After cleaning, the quantum efficiency was increased from 18% to 27% at 532nm and the electron escape probability was increased from 0.51 to 0.71.

Improved electric energy production of solar cell using small silver nanoparticles

The influence of small Ag nanoparticles (NPs) on the all-day electric energy production of solar cells has been investigated. The small Ag NPs were deposited on the cell surface by the magnetron sputtering system. The cell without NPs is used as a reference cell. The external quantum efficiency (EQE) curves indicate that the performance of cell with 8% nanoparticle coverage is better than that of other cells in the long wavelength band. The maximum power-angle curves indicate that the small Ag NPs can effectively improve the all-day electric energy production of solar cell. Comparing with the values of reference cell, the half peak height of maximum power for cell optimized increases by 65%, and the half peak breadth of maximum power for cell optimized broadens by 3%. The enhancements of optimum operating current and optimum operating voltage lead directly to the enhancement of maximum power.

CHClF2 gas mixtures to activate all-sputtered CdS/CdTe solar cells

Solar cell production process entirely based on sputtering deposition is considered the most suitable for industrial applications. Based-CdTe solar cells need activation treatment usually performed by CdCl2 saturated solution bath followed by high temperature annealing. Liquid, flammable and toxic reagents need special care in industrial processes. In this work, alternative activation treatments based on controlled gaseous atmospheres with Ar-O2-CHClF2 and Air-CHCl2 for all-sputtered CdTe solar cells were studied. Finished devices were compared to cells activated by CdCl2 saturated solution. The all-sputtered (glass/ITO/ZnO/CdS/CdTe) structures were characterized before and after the activation processes byX-ray diffraction and field emission scanning electron-microscopy. Solar cells were characterized by external quantum efficiency and current density-voltage curves. An efficiency of 11% was achieved for the solar cell activated with Ar-O2-CHClF2 gas mixture, achieving values of Voc=0.797V and Jsc=25.4mA/cm2. The quantum efficiency was around 90% in the 580–830nm range.

Quantum efficiency for reflection-mode varied doping negative-electron-affinity GaN photocathode

As a new kind of ultraviolet photocathode material, the negative-electron-affinity (NEA) GaN photocathode needs to further improve its photoemission performance and the stable performance in practical applications. Under the limit of GaN photocathode material growth level, how to further improve the quantum efficiency of cathode is an important problem. The varied doping technology can help to solve the problem under such circumstances. According to the photoemission mechanism of varying doping NEA GaN photocathode material, the built-in electric field formulas and the quantum efficiency formulas for reflection-mode varied doping NEA GaN photocathode are given. The preliminary structure of varied doping NEA GaN photocathode is designed. The varied doping material sample is divided into four layers according to the doping concentration. Using the self-developed experimental equipment, the varied doping GaN photocathode sample is activated with Cs/O. The activation process and the change characteristics of photocurrent for varied doping NEA GaN photocathode are discussed. At the beginning, the photocurrent is increased steady with the introduction of Cs, then the Cs kill phenomenon appears in the presence of excessive Cs. After the introduction of O, the photocurrent value starts to rise again. The spectral response of varied doping GaN photocathode is tested in situ after activation, and the quantum efficiency values ranging from 240 nm to 354 nm are obtained. On the basis of the obtained experimental results of quantum efficiency, combining to the typical quantum efficiency curve from University of California, the characteristics of quantum efficiency curves are analyzed. The results show that the quantum efficiency value for reflection-mode varied doping NEA GaN photocathode can reach 56% at 240 nm because of the built-in electric field, yet the quantum efficiency maximum value for uniform doping GaN photocathode is only 37% at 230 nm. The tested quantum efficiency maximum value of varied doping NEA GaN photocathode is improved much more than that of the uniform doping GaN photocathode. In a wider range of the incident light wavelength, the quantum efficiency of varied doping NEA GaN photocathode is relatively stable, and the excellent properties of varied doping GaN photocathode are confirmed. The reason why the value of quantum efficiency decreases with the increase of incident light wavelength is given. First, the photon energy decreases with the increase of incident light wavelength. Second, the incident light is absorbed from the front surface of cathode for reflection mode. In addition, the quantum efficiency curves of varied doping GaN photocathode show obvious sharp cut-off characteristics near the threshold, and the sharp cut-off characteristic is necessary for high detection sensitivity. The property of negative electron affinity for varied doping GaN cathode material after successful activation is also proved by the sharp cut-off feature.

Versatile plasmonic-effects at the interface of inverted perovskite solar cells.

Plasmonics is a highly promising approach to enhancing the light-harvesting properties of hybrid organic/inorganic perovskite solar cells. In the present work, our cells have a p-i-n inverted planar structure. An ultrathin NiO film with two different thicknesses of 5 and 10 nm prepared by a pulsed laser deposition process on an ITO substrate with a faceted and furrowed surface enabled the formation of a continuous and compact layer of well-crystallized CH3NH3PbI3via an anti-solvent chlorobenzene process. The coverage mechanism of the NiO film on the ITO was clearly demonstrated through the J-V and external quantum efficiency (EQE) curves. Moreover, the results demonstrated that the gold nanoislands (Au NIs) increased the power conversion efficiency to 5.1%, almost double that of the samples without Au NIs. This result is due to the excitation of surface plasmons, which is characterized by strong scattering and enhancement of the electric field in the vicinity of the Au NIs loaded at the interface between the NiO and perovskite films. Additionally, we observed an enhancement of the EQE at wavelengths shorter than the plasmon resonance peak. In the current state, we speculate that the plasmoelectric potential effect is considered to be a good explanation of the photocurrent enhancement at the off-resonance region. Our work provides good guidance for the design and fabrication of solar-energy-related devices employing NiO electrodes and plasmonic Au NIs.

23.2% laser processed back contact solar cell: fabrication, characterization and modeling

We describe the manufacturing process for interdigitated back contact back junction silicon solar cells based on laser processes, and present detailed results and analysis to our best cell efficiency of 23.24%. The manufacturing process features two laser doping steps, one for the boron doped emitter and one for the phosphorus doped back surface field. The saturation current densities of thermal oxide passivated laser doped regions are on par with furnace diffused silicon for high efficiency solar cells. Laser ablation locally defines the contact areas through the rear dielectric layer stack, and structures the rear aluminum metallization. The precision of the laser systems in conjunction with the optical setup yields line shaped doping traces with a width of 150 µm and a pitch below 500 µm. The measured optical and electrical properties of our solar cell agree well with 3D simulation results. The measured reflection, transmission, quantum efficiency and current voltage curves in dark and illuminated condition simultaneously agree well with simulation, based on the same data set, giving confidence in the result of a detailed free energy loss analysis. The bulk resistive and recombination losses are identified as the main loss contributors. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.