Increased Surface Recombination Research Articles

Temperature behaviour of mixed-cation mixed-halide perovskite solar cells. Analysis of recombination mechanisms and ion migration

In our study, we show that compositional engineering of the “A” site cation of ABX3 perovskite structure formed by a mix of organic and inorganic cations is an effective route to improve the thermal stability of perovskite solar cells (PSCs). In this work, mixed-cation mixed-halide PSCs have been fabricated and characterized with temperature, from 253 up to 333 K. The active layer based on CsRbFAMAPb(IBr)3 results in a more stable device compared to standard MAPbI3 devices. Electrical characterization reveals a decrease of the solar cell parameters with temperature. Using Impedance Spectroscopy (IS) characterization, we have estimated an activation energy for the halide ion migration of 0.63 ± 0.08 eV, an ion diffusion coefficient of 10−14 cm2 s−1, and a defect density of 7.27·1015 cm−3. To our knowledge, this is the first time that these parameters have been calculated in CsRbFAMAPb(IBr)3 based devices, resulting in improved values compared to MAPbI3 devices. The worsening of device performance for temperatures above 300 K is attributed to a decrease of the spiro-OMeTAD conductivity and the degradation of the perovskite/spiro-OMeTAD interface. It is shown that for low temperatures (from 253 to 323 K), Shockley-Red-Hall (SRH) recombination in the bulk governs, while for temperatures above 323 K the increase in surface recombination becomes dominant due to the presence of non-selective contacts. Numerical simulations using SILVACO ATLAS corroborate the role of SRH in the perovskite active layer for low and medium temperatures, and the crucial influence of spiro-OMeTAD transport properties in the device performance parameters.

Simulation-based investigation of junction-controlled narrow-band Si photodetector with vertical structure

Junction-controlled narrow-band Schottky photodetectors are very attractive in the optoelectronic systems that operate in a small spectral range, due to its high noise immunity, simple structure, and self-powered work mode. In this work, simulation was carried out to study the working mechanism of the junction-controlled narrow-band photodetector based on a vertical silicon Schottky structure. It is showed that the spectral response of the device is mainly dominated by the quasi-neutral region instead of the depletion region of the Schottky structure. Widening quasi-neutral region can obviously red-shift the peak wavelengths of both quasi-neutral region and depletion region, and suppress the device response to short wavelength light. As the doping concentration of the silicon substrate increases, a similar phenomenon can be observed due to the decrease of the diffusion length. Furthermore, increasing surface recombination velocity also can effectively reduce the quantum efficiency of the device at the wavelength <1060 nm. These results signify that junction-controlled narrow-band photodetectors of long-wavelength light can be realized by a variety of simple and feasible methods, indicating their promising application in future photoelectric systems.

Near-field thermophotovoltaic energy conversion analysis based on enhanced radiative absorption distribution

Near-field radiation has been widely shown to greatly boost the electrical power of thermophotovoltaic (TPV) cells. However, there is a lack of theoretical analysis exploring the important influences of near-field effects on radiative absorption distributions as well as TPV energy conversion performances. This work investigates the electrical performances of near-field TPV cells made of InGaSb coupled with different practical emitters such as plain tungsten (W), indium tin oxide (ITO) film, and alternate W and alumina multilayer in detail. A comprehensive analysis is conducted to systematically compare the impacts of evanescent wave tunneling, surface plasmon resonance, and hyperbolic modes on spatial distributions of radiative absorption and the profiles of local carrier concentrations. The detailed and accurate analysis reveals the crucial role of near-field radiation emitted by various emitters in charge collection efficiency, thermal photon flux penetration depth, and photocurrent generation. Thus, the results certify that the electric power could be enhanced by utilizing ITO and multilayer emitters instead of a plain W emitter. The efficiency for an ITO emitter increases with decreasing vacuum gap owing to the suppressed bulk recombination but decreases when the vacuum gap falls below 18 nm due to increased surface recombination. While the efficiency for a multilayer emitter is comparatively lower due to the larger sub-bandgap photons and inefficient n-region. Furthermore, we verify the strategies for performance improvement via decreasing the surface recombination and optimizing the p-region thickness. The underlying mechanism is interpreted based on the spatial distribution and the collection efficiency of minority carriers.

Increase of the surface recombination velocity at high bias voltage in silicon irradiated by neutrons to extremely high fluences

The upgrading of ionizing radiation detectors is an actual problem especially related to the high energy physics and space research experiments. The simplest way to restore the signal of the irradiation degraded detector is the increase of the detector bias voltage. This method is widely used worldwide, including high energy physics experiments in ATLAS and CMS. This work presents an effect, which was caused by increased bias voltage in detectors irradiated to extreme high neutron fluence at low temperature. The effect could be related to the increase of surface recombination velocity.The intrinsic photoconductivity spectra were exploited in order to investigate the properties of highly irradiated silicon as this effect depends on parameters that are important in radiation detectors. Two characteristic effects were observed in such highly irradiated samples: the increase of photoconductivity quantum yield and the enhancement of surface recombination at higher bias voltages. The increase of the quantum yield was analyzed in Ref. [1]. The increase of the surface recombination with bias electric field was analyzed in this work as an extension of the performed investigation in the same samples as in Ref. [1]. The investigated silicon samples were irradiated by neutrons to wide range fluence up to 1017 n/cm2.The origin of this effect was analyzed and related to the radiation clusters, which decrease the free carrier lifetime.

Inverted Pyramid Morphology Control by Acid Modification and Application for PERC Solar Cells.

Silicon inverted pyramid (IP) structures, with lower reflectance and increased surface recombination, are one of the best choices for light-trapping structures of high-efficiency silicon solar cells. The solution process of IP generally goes through three main steps: porous silicon etched by metal-assisted chemical etching, acid etching, and alkali anisotropic etching. In this paper, the role that acid modification plays in IP preparation and the application of our optimized texture for passivated emitter and rear solar cells (PERC) were investigated. Experimental results show that acid plays a decisive role in optimizing and modifying the morphology of porous silicon; thus, the morphology of porous silicon has no direct influence on the morphology of IP. In addition, the opening size of IP is mainly determined by the size of silicon micron holes modified by the acid process. PC1D simulation results manifest that IPs can increase the short-circuit current density (Jsc) of devices by 1.04 mA/cm2 and power conversion efficiency by 0.55%; hence, our optimized IP-based PERC achieve the highest simulative conversion efficiency of 23.21%. This is an effective and important way to manipulate the structure of IP, which points out the direction of fabrication and application of high-efficiency IP textures.

Increased surface recombination in crystalline silicon under light soaking due to Cu contamination

Light-induced degradation (LID) can occur in crystalline silicon (Si) due to increased recombination in the bulk or at the surfaces. As an example, copper (Cu) is a contaminant that reportedly causes LID in the bulk of Si under illumination. In this article, we show that Cu contamination can also increase recombination at the surface under illumination using surface saturation current density ( J 0 ) analysis. More specifically, in the presence of Cu we observed that J 0 increased from 14 fA/cm 2 to 330 fA/cm 2 in SiO 2 passivated Float Zone (FZ) Si, and from 11 fA/cm 2 to 200 fA/cm 2 in corresponding Czochralski (Cz) Si after illumination under an LED lamp (0.6 Suns, 80 °C). In reference samples without Cu contamination, the J 0 was unaffected. These results demonstrate that a significant increase in surface recombination is possible without the presence of hydrogen. Furthermore, hydrogen was not seen to affect the Cu-induced surface degradation as similar experiments made with hydrogenated silicon nitride (SiN x :H) did not show further increase in J 0 . However, the timescale of the observed degradation was relatively fast (hours) indicating that Cu-induced surface degradation is a separate phenomenon from the earlier reported surface-related degradation. • Cu contamination leads to increased surface recombination in Si under light soaking. • The phenomenon occurs in FZ and Cz Si with both SiO 2 and SiN x :H passivation. • Surface saturation current density J 0 remained at 10–15 fA/cm 2 in uncontaminated Si. • J 0 increased to 330 fA/cm 2 in FZ Si and to 200 fA/cm 2 in Cz Si during light soaking. • An increase in interfacial defect density was observed in Cu-contaminated samples.

Overcoming the Challenge of High Surface Recombination in Thin‐Film Photovoltaic Cells Based on Subwavelength Arrays for Elevated Light Trapping

Surface arrays of subwavelength photoactive structures have been demonstrated for photovoltaic (PV) applications with elevated omnidirectional and broadband absorption. However, this approach suffers from an increase in surface recombination and loss of photovoltage. Herein, surface decoration with subwavelength dielectric (SiO2) arrays that provide enhanced light trapping without compromising the photovoltage performance is proposed. An increase of ≈ 50% in broadband absorption is shown in an ultrathin film of 200 nm due to the presence of a top surface SiO2 nanopillar array in comparison with the same film decorated with an optimized antireflective coating of 50 nm of Si3N4. Interestingly, the broadband enhancement is not due to lower reflection, but rather the presence of the arrays forces a considerable lower transmission. The distribution of the optical power flux density suggests that the low transmission is due to appreciable refraction, which is induced by the presence of the dielectric arrays. Finally, the photovoltaic performance is examined for various array geometries and absorber acceptor concentrations and an overall increase of &gt;60% in PV efficiency is calculated for a decorated photovoltaic cell in comparison with a PV cell with an antireflection coating of 50 nm Si3N4.

Light-trapping structures for planar solar cells inspired by transformation optics.

Optimal light absorption is decisive in obtaining high-efficiency solar cells. An established, if not to say the established, approach is to texture the interface of the light-absorbing layer with a suitable microstructure. However, structuring the light-absorbing layer is detrimental concerning its electrical properties due to an increased surface recombination rate (owing to enlarged surface area and surface defects) caused by the direct patterning process itself. This effect lowers the efficiency of the final solar cells. To circumvent this drawback, this work theoretically explores a transformation optics (TrO) inspired approach to map the nanopatterned texture onto a planar equivalent. This offers a pattern with the same optical functionality but with much improved electrical properties. Schwarz-Christoffel mappings are used for ensuring conformality of the maps. It leads to planar, inhomogeneous, dielectric-only materials for the light trapping structure to be placed on top of the planar light-absorbing layer. Such a design strategy paves a way towards a novel approach for implementing light-trapping structures into planar solar cells.

The significance of the local structure of cobalt-based catalysts on the photoelectrochemical water oxidation activity of BiVO4

The local structures of the water oxidation catalysts play an important role in reaction kinetics and the performance of the photoanodes. In this study, we deposited cobalt-based catalysts on nanoporous BiVO4 with controlled thicknesses by atomic layer deposition (ALD). Despite the similar oxidation states of cobalt in all depositions, different water oxidation activities in neutral pH conditions were observed. A dramatic photocurrent raise, lowered kinetic overpotential, and smaller charge transfer resistance across the photoanode/electrolyte interface were achieved when a uniform ultrathin Co(OH)2 layer was formed on BiVO4. Photocurrent density for water oxidation showed a 95% enhancement at 0.6 V vs. RHE when the catalyst was in the form of Co(OH)2, while an 80% increase was obtained for CoO. Ideal coordination of Co(OH)2 on hydroxylated BiVO4 surface assists the charge transfer between the electrolyte and BiVO4 without increasing surface recombination. The results of this study emphasize the importance of controlling the local structure of the catalysts in the performance of the water splitting photoanodes.

Texturization of diamond wire sawn multi-crystalline silicon wafers by micro-droplet etching

Diamond wire sawn multicrystalline silicon (DWS mc-Si) solar cell wafers have been known to be difficult to texturize by conventional acidic wet etching texturization process. A novel texturization method based on localized micro-droplet etching (MDE) has been developed, in which the micro-droplet is generated by controlled condensation of thermal vapor from a HF–HNO3–H2O bath. Uniformly distributed micron scale etch-pit type surface textures on DWS mc-Si wafers are made by the MDE process. Their light reflectivity is reduced to 18–21%, and their sawmarks are removed. Full size DWS mc-Si wafer samples were MDE textured, and send to a solar cell fabrication line along with the conventionally wet textured DWS mc-Si wafers as reference, without any adjustment of processing parameters for the MDE textured wafers. The average short circuit current of the MDE textured cells has been found to increase as compared to the reference cells, in a relative ratio approximately matching the final light reflection reduction ratio induced by the MDE textures. The average open circuit voltage and fill factor of the MDE textured cells are found to increase slightly, indicating that the MDE texture has not induced any significant increase in surface recombination of carriers, neither poorer contact of printed grid contact on cell surfaces. In average, 0.52% absolute increase of energy conversion efficiency is obtained.

Reducing ultraviolet-induced open-circuit voltage loss in inverted organic solar cells by maintaining charge selectivity of the electron collection contact using polyethylenimine

The effect of using Polyethylenimine (PEI) instead of ZnO in the electron extraction layers (EELs) of inverted organic solar cells (OSCs) on their photo-stability behavior is investigated. Studies on inverted OSCs based on two different donor/acceptor bulk heterojunction material systems show that replacing ZnO by PEI substantially reduces the open-circuit voltage (Voc) loss in OSCs that is often observed under prolonged UV irradiation. Analysis of current density-voltage characteristics of the solar cells as well as of hole-only devices shows that the higher Voc stability attained upon using PEI instead of ZnO is mainly due to the ability of the ITO/PEI contact to maintain a higher degree of electron selectivity and hole blocking properties under UV exposure in comparsion to the ITO/ZnO contact. Using Voc vs light intensity analysis, a UV-induced transition in the dominant recombination mechanism from a trap-assisted bulk recombination mechanism to a surface recombination one at the contacts is found to occur in solar cells with ZnO EELs. Similar tests on PEI show that it suppresses that increase in surface recombination and confirms its ability to maintain the hole blocking properties of the contact upon UV exposure. This study provides a direct observation of increased surface recombination in OSCs due to UV irradiation and direct evidence of the importance of maintaining charge selectivity of contacts to suppress surface recombination and maintain high Voc photo-stability.

Investigation of Well-Defined Pinholes in TiO2 Electron Selective Layers Used in Planar Heterojunction Perovskite Solar Cells.

The recently introduced perovskite solar cell (PSC) technology is a promising candidate for providing low-cost energy for future demands. However, one major concern with the technology can be traced back to morphological defects in the electron selective layer (ESL), which deteriorates the solar cell performance. Pinholes in the ESL may lead to an increased surface recombination rate for holes, if the perovskite absorber layer is in contact with the fluorine-doped tin oxide (FTO) substrate via the pinholes. In this work, we used sol-gel-derived mesoporous TiO2 thin films prepared by block co-polymer templating in combination with dip coating as a model system for investigating the effect of ESL pinholes on the photovoltaic performance of planar heterojunction PSCs. We studied TiO2 films with different porosities and film thicknesses, and observed that the induced pinholes only had a minor impact on the device performance. This suggests that having narrow pinholes with a diameter of about 10 nm in the ESL is in fact not detrimental for the device performance and can even, to some extent improve their performance. A probable reason for this is that the narrow pores in the ordered structure do not allow the perovskite crystals to form interconnected pathways to the underlying FTO substrate. However, for ultrathin (~20 nm) porous layers, an incomplete ESL surface coverage of the FTO layer will further deteriorate the device performance.

Reducing the Surface Area of Black Silicon by Optically Equivalent Structures

Black silicon is a promising low-cost technology to boost the efficiency of solar cells. The large surface area of black silicon, however, imposes challenges such as increased surface recombination and Auger recombination in doped nanostructures. This issue motivates the search for structures with lower surface area but similar optical properties. Here, we identify an approach for reducing the surface area of black silicon, while maintaining optical performance. Specifically, we have demonstrated via simulations that wavelength-scale arrays of nanotapers have similar antireflection properties as black silicon, but with less than half of the surface area. Additionally, we highlight that the light-trapping properties of black silicon are not optimal, and that its performance can be further improved by using nanostructures with controlled scattering properties. We quantify the optical performance of the structures and their surface area, thus identifying optically equivalent structures with reduced surface areas. We believe that these findings will help to boost the efficiency of devices based on black silicon.

Enhanced metal assisted etching method for high aspect ratio microstructures: Applications in silicon micropillar array solar cells

A solar cell device, fabricated on high density array cylindrical pillars, enables photogenerated carrier collection in the radial direction, thus shortening the path length of the carriers reaching the junction. It also provides advantages over conventional planar junction solar cells, such as reduced surface reflectance and enhanced light trapping. In this study, highly ordered Si micropillars were fabricated by photolithography and metal assisted etching (MAE) methods. It is shown that the use of ethanol as a solvent during the etching process and increasing HF concentration in the MAE solution both improve the quality of the surfaces of the pillars. Micropillars with smooth sidewalls and a high aspect ratio were obtained in this way. Solar cells with a radial junction were then fabricated on these micropillars. Standard doping, SiO2/SiNx passivation, and metallisation steps were carried out for the fabrication of solar cells with different micropillar lengths. A significant decrease in reflectance values was observed as the micropillar length increased, as expected. Solar cell short circuit current density (Jsc) and efficiency (η) of the solar cells tended to increase with micropillar length up to 11.5 µm and then decrease due to increased surface recombination. The maximum efficiency achieved in this study is 17.26%.

Physics of potential-induced degradation in bifacial p-PERC solar cells

The combination of increasing operational voltages beyond 1000 V in photovoltaic (PV) installations and the emergence of new PV technologies requires a critical assessment of the susceptibility to potential-induced degradation (PID). Since this failure mode can trigger significant and rapid power losses, it is considered among the most critical failure modes with a high financial impact. Insights in the physical mechanism of the performance loss and its driving factors are critical to develop adapted characterization methods and mitigation solutions. PID in p-type solar cells is triggered by sodium (Na) that diffuses into stacking faults of the silicon lattice, causing shunt paths through the pn-junction. In addition, it is hypothesised that for bifacial p-PERC solar cells positive charges, such as Na+, accumulate in/on the negatively charged AlOx rear passivation layer due to the potential difference between the glass and the rear cell surface. This significantly increases surface recombination. However, the degradation behaviour observed in bifacial monocrystalline p-PERC solar cells under PID stress from both sides (bifacial PID stress) does not match with just one of the degradation mechanisms. A comprehensive test matrix was carried out to understand the physical origin of PID in front emitter bifacial p-PERC solar cells in a glass/glass packaging. The results show that bifacial p-PERC solar cells under bifacial PID stress suffer from both shunting of the pn-junction and increased surface recombination at their rear side. Hereby, we prove that the glass/glass packaging in combination with bifacial solar cells can significantly increase the severity of PID.

Increasing Photoluminescence Quantum Yield by Nanophotonic Design of Quantum-Confined Halide Perovskite Nanowire Arrays.

High-photoluminescence quantum yield (PLQY) is required to reach optimal performance in solar cells, lasers, and light-emitting diodes (LEDs). Typically, PLQY can be increased by improving the material quality to reduce the nonradiative recombination rate. It is in principle equally effective to improve the optical design by nanostructuring a material to increase light out-coupling efficiency (OCE) and introduce quantum confinement, both of which can increase the radiative recombination rate. However, increased surface recombination typically minimizes nanostructure gains in PLQY. Here a template-guided vapor phase growth of CH3NH3PbI3 (MAPbI3) nanowire (NW) arrays with unprecedented control of NW diameter from the bulk (250 nm) to the quantum confined regime (5.7 nm) is demonstrated, while simultaneously providing a low surface recombination velocity of 18 cm s-1. This enables a 56-fold increase in the internal PLQY, from 0.81% to 45.1%, and a 2.3-fold increase in OCEy to increase the external PLQY by a factor of 130, from 0.33% up to 42.6%, exclusively using nanophotonic design.

(Invited) Interfacial Engineering of Energy Conversion and Storage Materials Using Atomic Layer Deposition

Nanoscale materials offer several unique opportunities for applications in energy conversion and storage, due to their high surface-to-volume ratios, short transport distances, mechanical strain relaxation, and the ability to tune their material properties. However, despite these potential advantages, increasing surface and interfacial area dramatically can also present challenges. For example, in semiconductor devices such as photovoltaics and photoelectrochemical cells, an increase in surface recombination of excited charge carriers can offset the benefits of nanostructuring. Similarly, in batteries, undesirable side reactions at electrode-electrolyte interfaces, such as electrolyte decomposition and surface passivation, can lead to degradation of performance and limit lifetime. Therefore, in electrochemical engineering of nanostructured electrode materials, we desire the ability to “turn on” the desirable properties, and “turn off” the deleterious effects of moving to the nanoscale. To improve our ability to precisely control surface and interfacial phenomena in nanoscale materials, we require new methods to control surface chemistry and structure with atomic precision, without introducing inhomogeneities that may arise from diffusion limits during surface modification. One technique that simultaneously accomplishes both of these traits is Atomic Layer Deposition (ALD). In the past two decades, there has been an explosion of research in ALD for interfacial modification of nanostructured materials for energy conversion and storage. However, much of this work has been empirical in nature, and there is often a fundamental lack of understanding of the coupled surface chemistry, structure, and performance relationships at the atomic scale. To overcome this limitation, we must complement ALD interfacial modification with atomically-precise characterization methods. We must also pay attention to not only the initial and final surface properties, but develop novel in situ/operando methods to quantitatively evaluate the evolution of surface properties during dynamic device operation. To bridge this gap, our research group focuses on using ALD not only as a tool for surface coating, but as a platform for fundamental research on the coupled surface chemical, electrochemical, structural, and mechanical evolution that occurs during operation. In this talk, I will present examples in our work on atomically-precise control of electrode-electrolyte interfaces in rechargeable batteries and photoelectrochemical cells. Examples will include development of superionic lithium solid electrolytes by ALD that enable conformal coating of 3-D battery architectures and interfacial modification of all-solid-state batteries1, control of lithium metal anode electrodeposition and dissolution2, and fabrication of 3-D hierarchical photoelectrodes for artificial photosynthesis and water purification3,4. Common to each of these examples is the ability to decouple beneficial and detrimental processes that occur at the interface, and perform materials design optimization at the atomic scale. Beyond purely performance metrics, and emphasis will be placed on gaining new fundamental mechanistic insight into the origins of improved surface behavior, which provides a perspective on the opportunities that surface and interfacial engineering at the atomic scale provides. E. Kazyak, K.-H. Chen, K. N. Wood, A. L. Davis, T. Thompson, A.R. Bielinski, A. J. Sanchez, X. Wang, C. Wang, J. Sakamoto, N. P. Dasgupta, Chem. Mater. 29, 3785 (2017)E. Kazyak, K. N. Wood and N. P. Dasgupta, Chem. Mater. 27, 6457 (2015).E. Rodríguez, S. P. Agarwal, S. An, E. Kazyak, D. Das, W. Shang, R. Skye, T. Deng, and N. P. Dasgupta, ACS Appl. Mater. Interfaces 10, 4614 (2018)Lee, A. R. Bielinski, E. Fahrenkrug, N. P. Dasgupta, and S. Maldonado, ACS Appl. Mater. Interfaces. 8, 16178 (2016)

Competition between H and CO for Active Sites Governs Copper‐Mediated Electrosynthesis of Hydrocarbon Fuels

AbstractThe dynamics of carbon monoxide on Cu surfaces was investigated during CO reduction, providing insight into the mechanism leading to the formation of hydrogen, methane, and ethylene, the three key products in the electrochemical reduction of CO2. Reaction order experiments were conducted at low temperature in an ethanol medium affording high solubility and surface‐affinity for carbon monoxide. Surprisingly, the methane production rate is suppressed by increasing the pressure of CO, whereas ethylene production remains largely unaffected. The data show that CH4 and H2 production are linked through a common H intermediate and that methane is formed through reactions among adsorbed H and CO, which are in direct competition with each other for surface sites. The data exclude the participation of solution species in rate‐limiting steps, highlighting the importance of increasing surface recombination rates for efficient fuel synthesis.

Junction model and transport mechanism in hybrid PEDOT:PSS/n-GaAs solar cells

This study investigates the junction formation and interface properties of PEDOT:PSS/n-GaAs hybrid solar cells on planar GaAs substrates. Barrier height, photocurrent, dark saturation current and build-in potential at this hybrid interface are measured by varying n-GaAs doping concentrations. The work function and valence band edge of the polymer are extracted from ultraviolet photoelectron spectroscopy to construct the band diagram of the hybrid n-GaAs/PEDOT:PSS junction. The current-voltage characteristics were analyzed by using abrupt (p+n) junction and Schottky junction models. Contrary to the earlier results from the PEDOT:PSS/n-Si solar cells, the experimental evidence clearly suggested that the interface between n-GaAs and PEDOT:PSS more likely exhibited a Schottky type instead of a p+n junction. The current transport is governed by the thermionic emission of majority carriers over a barrier and not by diffusion. The dark saturation current density increases markedly owing to the increasing surface recombination rate in heavier n-doped GaAs substrates, leading to significant deterioration in solar cells performance.

Hybrid silicon honeycomb/organic solar cells with enhanced efficiency using surface etching

Silicon (Si) nanostructure-based photovoltaic devices are attractive for their excellent optical and electrical performance, but show lower efficiency than their planar counterparts due to the increased surface recombination associated with the high surface area and roughness. Here, we demonstrate an efficiency enhancement for hybrid nanostructured Si/polymer solar cells based on a novel Si honeycomb (SiHC) structure using a simple etching method. SiHC structures are fabricated using a combination of nanosphere lithography and plasma treatment followed by a wet chemical post-etching. SiHC has shown superior light-trapping ability in comparison with the other Si nanostructures, along with a robust structure. Anisotropic tetramethylammonium hydroxide etching not only tunes the final surface morphologies of the nanostructures, but also reduces the surface roughness leading to a lower recombination rate in the hybrid solar cells. The suppressed recombination loss, benefiting from the reduced surface-to-volume ratio and roughness, has resulted in a high open-circuit voltage of 600 mV, a short-circuit current of 31.46 mA cm−2 due to the light-trapping ability of the SiHCs, and yields a power conversion efficiency of 12.79% without any other device structure optimization.