Photovoltaic Materials Research Articles

A Novel Thiazole‐Core Spacer Based Dion–Jacobson Perovskite with Type II Quantum Well Structure for Efficient Photovoltaics

Abstract2D Dion–Jacobson (DJ) perovskites show structural stability and tunability and are regarded as promising photovoltaic materials. The spacer cations play an important impact on exciton separation and charge transport of 2D perovskites. Herein, a novel spacer with thiazole as core, 2‐thiazolemethanammonium (AMT), owning characters of small molecular size, delocalized π‐electrons, and strong electron‐withdrawing ability, is introduced to construct 2D DJ perovskites. Owing to the strong orbital coupling between AMT spacer and inorganic layers, the AMT‐based perovskite exhibits type II quantum well structure, which is favorable for exciton separation. On contrary, such interaction does not appear in the DJ perovskite when aliphatic propyldiammonium (PDA), with a similar length, is used as spacer. The AMT spacer can also induce better crystallinity, resulting in reduced defect density and improved charge transport ability. The optimized device based on (AMT)MA3Pb4I13 exhibits a power conversion efficiency (PCE) of 19.69%, which is a record for 2D DJ perovskite solar cells (PSCs) (n ≤ 4). This work provides deep understanding of the impact of aromatic spacer on the electronic structure of 2D DJ perovskites and the corresponding photovoltaic performance and provides a new opportunity toward highly efficient and stable PSCs.

Surface photogalvanic effect in Ag2Te

The bulk photovoltaic effect (BPVE) in non-centrosymmetric materials has attracted significant attention in recent years due to its potential to surpass the Shockley-Queisser limit. Although these materials are strictly constrained by symmetry, progress has been made in artificially reducing symmetry to stimulate BPVE in wider systems. However, the complexity of these techniques has hindered their practical implementation. In this study, we demonstrate a large intrinsic photocurrent response in centrosymmetric topological insulator Ag2Te, attributed to the surface photogalvanic effect (SPGE), which is induced by symmetry reduction of the surface. Through diverse spatially-resolved measurements on specially designed devices, we directly observe that SPGE in Ag2Te arises from the difference between two opposite photocurrent flows generated from the top and bottom surfaces. Acting as an efficient SPGE material, Ag2Te demonstrates robust performance across a wide spectral range from visible to mid-infrared, making it promising for applications in solar cells and mid-infrared detectors. More importantly, SPGE generated on low-symmetric surfaces can potentially be found in various systems, thereby inspiring a broader range of choices for photovoltaic materials.

Assessment of photovoltaic power generation and radiative cooling potentials in old residential districts: A case study of Shenzhen

Building-integrated photovoltaic (PV) and radiative cooling (RC) are promising technologies for attaining the zero-carbon target in building industry. The PV and RC materials can be utilized for energy-saving renovations in building envelopes of existing residential districts. Nowadays, it is common practice to add thermal insulation to old residential districts to reduce building energy consumption. Whereas the development of PV and RC technologies provide opportunities of renewable energy utilization on building envelops in old residential districts renovation. The space for installing PV and RC materials on the roofs and facades is restricted. Hence, assessing and contrasting the efficacy of PV and RC materials in different sections of building envelopes is important from both energy and economic aspects consideration.This study employed the Rhino-Grasshopper platform to assess the energy and economic performances of PV and RC technologies when installed on roofs and facades with varying orientations. A typical old residential district in Shenzhen was employed as an example. The objective was to enhance the allocation of PV and RC components to attain optimal energy and economic outcomes. The life-cycle equivalent energy saving was used as economic indicator. Results demonstrated that PV is more suitable on roofs application, whereas RC is more suitable for facades. It is profitable to apply RC on the north facade whereas PV can be profitable when applied to the other envelops. By applying PV and RC to all old residential districts in Shenzhen, the annual PV power generation and cooling energy saving from RC are as high as 5299 GWh and 277 GWh. This study demonstrated that PV and RC are promising technologies in energy-saving renovation of old residential districts. The developed methodology can be applied in renovation projects to achieve optimized designs.

Non-contact intelligent sensor for recognizing transparent and naked-eye indistinguishable materials based on ferroelectric BiFeO3 thin films

At present, the research on ferroelectric photovoltaic materials mainly focuses on photoelectric detection. In the context of the rapid development of the Internet of Things (IoT), it is particularly important to use smaller thin-film devices as sensors. In this work, an indium tin oxide/bismuth ferrite (BFO)/lanthanum nickelate device has been fabricated on an F-doped tin oxide glass substrate using the sol–gel method. The sensor can continuously output photoelectric signals with little environmental impact. Compared to other types of sensors, this photoelectric sensor has an ultra-low response time of 1.25 ms and ultra-high sensitivity. Furthermore, a material recognition system based on a BFO sensor is developed. It can effectively identify eight kinds of materials that are difficult for human eyes to distinguish. This provides new ideas and methods for developing the IoT in material identification.

Theoretical Design of Tellurium-Based Two-Dimensional Perovskite Photovoltaic Materials.

In recent years, the photoelectric conversion efficiency of three-dimensional (3D) perovskites has seen significant improvements. However, the commercial application of 3D perovskites is hindered by stability issues and the toxicity of lead. Two-dimensional (2D) perovskites exhibit good stability but suffer from low efficiency. Designing efficient and stable lead-free 2D perovskite materials remains a crucial unsolved scientific challenge. This study, through structural prediction combined with first-principles calculations, successfully predicts a 2D perovskite, CsTeI5. Theoretical calculations indicate that this compound possesses excellent stability and a theoretical efficiency of up to 29.3%, showing promise for successful application in thin-film solar cells. This research provides a new perspective for the design of efficient and stable lead-free 2D perovskites.

Exploration of the synergistic effect of chrysene-based core and benzothiophene acceptors on photovoltaic properties of organic solar cells

To improve the efficacy of organic solar cells (OSCs), novel small acceptor molecules (CTD1–CTD7) were designed by modification at the terminal acceptors of reference compound CTR. The optoelectronic properties of the investigated compounds (CTD1–CTD7) were accomplished by employing density functional theory (DFT) in combination with time-dependent density functional theory (TD-DFT). The M06 functional along with a 6-311G(d,p) basis set was utilized for calculating various parameters such as: frontier molecular orbitals (FMO), absorption maxima (λmax), binding energy (Eb), transition density matrix (TDM), density of states (DOS), and open circuit voltage (Voc) of entitled chromophores. A red shift in the absorption spectra of all designed chromophores (CTD1–CTD7) was observed as compared to CTR, accompanied by low excitation energy. Particularly, CTD4 was characterized by the highest λmax value of 685.791 nm and the lowest transition energy value of 1.801 eV which might be ascribed to the robust electron-withdrawing end-capped acceptor group. The observed reduced binding energy (Eb) was linked to an elevated rate of exciton dissociation and substantial charge transfer from central core in HOMO towards terminal acceptors in LUMO. These results were further supported by the outcomes from TDM and DOS analyses. Among all entitled chromophores, CTD4 exhibited bathochromic shift (685.791 nm), minimum HOMO/LUMO band gap of 2.347 eV with greater CT. Thus, it can be concluded that by employing molecular engineering with efficient acceptor moieties, the efficiency of photovoltaic materials could be improved.

Steric hindrance induced low exciton binding energy enables low‐driving‐force organic solar cells

AbstractExciton binding energy (Eb) has been regarded as a critical parameter in charge separation during photovoltaic conversion. Minimizing the Eb of the photovoltaic materials can facilitate the exciton dissociation in low‐driving force organic solar cells (OSCs) and thus improve the power conversion efficiency (PCE); nevertheless, diminishing the Eb with deliberate design principles remains a significant challenge. Herein, bulky side chain as steric hindrance structure was inserted into Y‐series acceptors to minimize the Eb by modulating the intra‐ and intermolecular interaction. Theoretical and experimental results indicate that steric hindrance‐induced optimal intra‐ and intermolecular interaction can enhance molecular polarizability, promote electronic orbital overlap between molecules, and facilitate delocalized charge transfer pathways, thereby resulting in a low Eb. The conspicuously reduced Eb obtained in Y‐ChC5 with pinpoint steric hindrance modulation can minimize the detrimental effects on exciton dissociation in low‐driving‐force OSCs, achieving a remarkable PCE of 19.1% with over 95% internal quantum efficiency. Our study provides a new molecular design rationale to reduce the Eb.

The chemistry of heterocycles in the 21st century

The chemistry of heterocyclic compounds has traditionally been and remains a bright area of chemical science in Russia. This is due to the fact that many heterocycles find the widest application. These compounds are the key structural fragments of most drugs, plant protection agents. Many natural compounds are also derivatives of heterocycles. At present, more than half of the hundreds of millions of known chemical compounds are heterocycles. This collective review is devoted to the achievements of Russian chemists in this field over the last 15–20 years. The review presents the achievements of leading heterocyclists representing both RAS institutes and university science. It is worth noting the wide scope of the review, both in terms of the geography of author teams, covering the whole of our large country, and in terms of the diversity of research areas. Practically all major types of heterocycles are represented in the review. The special attention is focused on the practical applications of heterocycles in the design of new drugs and biologically active compounds, high-energy molecules, materials for organic electronics and photovoltaics, new ligands for coordination chemistry, and many other rapidly developing areas. These practical advances would not be possible without the development of new fundamental transformations in heterocyclic chemistry.<br> Bibliography — 2237 references.

Combining Trivalent Ion-Doping with Halide Alloying to Increase the Efficiency of Tin Perovskites.

Tin-halide perovskites (THP) are emerging materials for photovoltaics with optoelectronic properties potentially rivaling lead-based analoges. Their efficiencies in solar cells are, however, severely limited by the high sensitivity of tin to oxygen and the heavy p-doping natively present in the material. While the effects of oxygen can be mitigated by using reducing agents upon the synthesis and by encapsulating the device, the native p-doping caused by the high density of acceptor defects remains a challenge to be further addressed for prolonging carrier lifetimes and, consequently, device efficiency. In this work, potential compositional engineering strategies aimed at reducing the p-doping of this class of materials and increasing their efficiency in solar cells are investigated. Based on density functional theory simulations it is demonstrated that THP doping with d1s2 trivalent ions effectively decreases the hole background density and the density of the deep defects responsible for the non-radiative recombination in these materials. This effect is enhanced by alloying iodide with small fractions of bromide, up to 33%. Higher bromide fractions, instead, are detrimental due to the increased non-radiative recombination. These results may provide useful guidelines to experimentalists for improving the optoelectronic quality of THPs and consequently of the ensuing devices.

Elucidating the potential of nitrogen-containing heterocyclic core-based non-fullerene acceptors for organic photovoltaic applications

Intramolecular noncovalent interactions are recognized as an efficient route to construct non-fused-core-based non-fullerene acceptors (NFAs) for efficient and cost-effective organic solar cells (OSCs). Herein, we engineered ten distinct structured NFAs molecules based on nitrogen-containing six-membered heterocycle cores. We incorporated various efficient functional groups into the synthetic reference molecule (RM) to design a new efficient series of NFAs (RM1-RM10). These materials are intensively investigated by performing advanced quantum chemical simulations, and the results are compared with those of synthetic RM molecules. We revealed the potential of these materials by investigating their optical, electronic, optoelectronic, and photovoltaic characteristics. By implementing various theoretical models, we explore the inner hidden potential of this designed series (RM1-RM10), such as density of state, transition density matrix, and electrostatic potential studies have been performed. Our applied theoretical modeling approach enables these photovoltaic materials (RM1-RM10) to have customized attributes by tuning their energy levels, binding energy, optical features, and also the photovoltaic characteristics of these materials. Newly developed molecules (RM1-RM10) show promising optoelectronic properties, including a lower energy gap (ranging from 1.81 eV to 1.63 eV) and an absorbed maximum absorption wavelength (760.36 nm), compared to the reference values, which have an energy gap of 1.81 eV and a wavelength of 684.16 nm. Moreover, to demonstrate the charge transfer behavior of these materials, a donor: acceptor (PTB7-Th:RM9) complex study is also performed to reveal the charge transfer phenomenon at the donor: acceptor interface. Therefore, our presented molecular modeling strategy holds significant potential for manufacturing materials with tailored qualities, which is crucial in advancing the organic photovoltaics field.

Optimizing inorganic SnS/ZrS2 heterojunction solar cells: Numerical analysis and performance insights

The SnS and ZrS2 have emerged as promising photovoltaic materials. This paper gives the first numerical analysis of inorganic SnS/ZrS2 heterojunction solar cells using SCAPS-1D. The study focuses on the effect of several parameters, such as thickness, doping charge carrier concentration, and energy bandgap, on fundamental solar cell properties in both the window and active layers. Our findings show that a variety of parameters influence solar cell performance, including built-in voltage, minority charge carrier lifetime, depletion breadth, charge carrier collection length, photogenerated current, and recombination rate. The maximum efficiency (η) attained in our simulated devices was 32.13 %, with FF of 84.51 % and Voc of 0.796 V. To achieve this efficiency, particular SnS parameters were used, such as a band gap of 1.00 eV, thickness of 5.0 μm, and doping charge carrier concentration of 1020 cm−3. In ZrS2, characteristics such as a band gap of 1.2 eV, thickness of 0.2 μm, and doping charge carrier content optimized 1020 cm−3 contribute to the observed efficiency. Our simulation results indicate that inorganic SnS/ZrS2 heterojunction devices have potential for solar device production that is cost-effective, large-scale, and high-efficiency. High performance enables a new path toward clean energy.

Studying the Thermodynamic Phase Stability of Organic-Inorganic Hybrid Perovskites Using Machine Learning.

As an important photovoltaic material, organic-inorganic hybrid perovskites have attracted much attention in the field of solar cells, but their instability is one of the main challenges limiting their commercial application. However, the search for stable perovskites among the thousands of perovskite materials still faces great challenges. In this work, the energy above the convex hull values of organic-inorganic hybrid perovskites was predicted based on four different machine learning algorithms, namely random forest regression (RFR), support vector machine regression (SVR), XGBoost regression, and LightGBM regression, to study the thermodynamic phase stability of organic-inorganic hybrid perovskites. The results show that the LightGBM algorithm has a low prediction error and can effectively capture the key features related to the thermodynamic phase stability of organic-inorganic hybrid perovskites. Meanwhile, the Shapley Additive Explanation (SHAP) method was used to analyze the prediction results based on the LightGBM algorithm. The third ionization energy of the B element is the most critical feature related to the thermodynamic phase stability, and the second key feature is the electron affinity of ions at the X site, which are significantly negatively correlated with the predicted values of energy above the convex hull (Ehull). In the screening of organic-inorganic perovskites with high stability, the third ionization energy of the B element and the electron affinity of ions at the X site is a worthy priority. The results of this study can help us to understand the correlation between the thermodynamic phase stability of organic-inorganic hybrid perovskites and the key features, which can assist with the rapid discovery of highly stable perovskite materials.

Balancing miscibility and crystallinity enables high-efficiency organic solar cells via ternary copolymerization

Due to the limited exciton diffusion length and relatively low charge carrier mobilities of organic photovoltaic materials, donor/acceptor blends in organic solar cells (OSCs) have to form nanoscale interpenetrating network morphology with orderly molecular stacking to simultaneously ensure exciton diffusion to donor/acceptor interfaces and charge carrier transport to electrodes. Herein, two terpolymer donors, XD1 and XD2, are developed via inserting N-ethyl-2,2′-bithiophene-3,3′-dicarboximide (BTI) unit into the molecular skeleton of D18 on account of the traits of BTI. The crystallinity and miscibility of terpolymer donors increase along with the BTI ratio. The dual functions of introducing BTI make polymer:Y6 blend films exhibit the tendency of first improving then deteriorating in crystallinity, phase separation, trap density and thus charge carrier dynamics, resulting in short-circuit current density and fill factor of OSCs to present the same trend. Among them, XD1:Y6 based OSCs well balance the dual functions of introducing BTI to acquire the optimized morphology, and thus achieve an impressive power conversion efficiency (PCE) of 19.13 %, which is among the highest values of OSCs. This work not only affords guidelines for developing high-performance terpolymer donors, but also demonstrates the importance of juggling crystallinity and miscibility of organic photovoltaic materials to boost PCEs of OSCs.

Design and Performance of Small-Molecule Donors with Donor-π-Acceptor Architecture Toward Vacuum-Deposited Organic Photovoltaics Having Heretofore Highest Short-Circuit Current Density.

The development of high-performance organic photovoltaic materials is of crucial importance for the commercialization of organic solar cells (OSCs). Herein, two structurally simple donor-π-conjugated linker-acceptor (D-π-A)-configured small-molecule donors with methyl-substituted triphenylamine as D unit, 1,1-dicyanomethylene-3-indanone as A unit, and thiophene or furan as π-conjugated linker, named DTICPT and DTICPF, are developed. DTICPT and DTICPF are facilely prepared via a two-step synthetic process with simple procedures. DTICPF with a furan π-conjugated linker exhibits stronger and broader optical absorption, deeper highest occupied molecular orbital (HOMO) energy levels, and better charge transport, compared to its thiophene analog DTICPT. As a result, vacuum-deposited OSCs based on DTICPF: C70 show an impressive power conversion efficiency (PCE) of 9.36% (certified 9.15%) with short-circuit current density (Jsc) up to 17.49mA cm-2 (certified 17.56mA cm-2), which is the highest Jsc reported so far for vacuum-deposited OSCs. Besides, devices based on DTICPT: C70 and DTICPF: C70 exhibit excellent long-term stability under different aging conditions. This work offers important insights into the rational design of D-π-A configured small-molecule donors for high efficient and stable vacuum-deposited OSCs.

Assessing the light scattering properties of c-Si PV module materials for agrivoltaics: Towards more homogeneous light distribution in crop canopies

Increasing the diffusivity of transmitted light at crop canopies in agrivoltaic (AV) systems remains a desired objective. This is because diffuse light increases the uniformity of light distribution and penetrates deeper into compact crop canopies thereby enhancing the photosynthesis rate and crop yields. Current approaches in greenhouses and open horticultural systems involve the use of diffusing films, diffuse glass, and light diffusing coatings. While these methods are effective, their combination with photovoltaic (PV) modules in AV greenhouses and other AV farming practices remain relatively unknown. However, little to no work has been done to assess the light scattering properties of the existing PV module structural materials such as the glass, encapsulants and the transparent backsheet. This work therefore investigates the light scattering behaviour of c-Si PV module materials through haze and Hortiscatter measurements. 18 samples with the structural layout of glass/encapsulant/encapsulant/back cover (glass or transparent polymer backsheet), applying different commercial encapsulants, were manufactured and tested experimentally. Light in the photosynthetic spectrum was used in the optical characterization of the samples. Furthermore, the impact of UV degradation on the haziness was also tested and the uniformity of the light distribution was further assessed to obtain the Hortiscatter. The findings indicated that (i) Transparent backsheets increased the light diffusivity. (ii) UV degradation reduced the light scattering of most of the PV materials. (iii) For the haziest transparent backsheet sample, the distribution of the transmitted light increased with the incidence light angle and reduced with increasing wavelength in the visible spectrum (iv) Highest haze and Hortiscatter values of up to 80% and 84% respectively were obtained for a sample with glass/TPO/TPO/transparent backsheet layout. (v) Haze and Hortiscatter values could help in optimising the PV module bill of materials for AV applications.

Modelling, analysis and forecasting of photovoltaic waste in Malaysia towards sustainable recycling by 2050

Malaysia is currently pushing for greater solar photovoltaic (PV) penetration through various policies, hence need to assess the consequent PV waste situation in preparation for sustainable End-of-Life (EoL) management of the PV systems. Through incorporation of fixed-loss, early-loss, and regular-loss scenarios into Malaysia's PV roadmap, it is projected that 229,009.17 tons to 481,137.12 tons of PV waste would be generated by 2050. Implementing current achievable PV material recovery rates would result in economic value creation between RM 1.02-2.21 billions (USD 213.78-463.92 millions) and carbon emissions avoidance between 398,858.41 tons CO2-eq to 785,712.93 tons CO2-eq by 2050. With crystalline silicon (c-Si) technology contributing more than 60% of waste share, 2029 to 2039 would be the suitable time period to jumpstart recycling operation due to consistent annual c-Si waste input of 8,000 tons/y for financially sustainable recycling. These findings can help garner support for sustainable EoL management of PV waste in Malaysia.

Advancing optoelectronic characteristics of Diketopyrrolopyrrole-Based molecules as donors for organic and as hole transporting materials for perovskite solar cells

A stable and efficient hole-transport material (HTM) is crucial for high-performance perovskite solar cells (PSCs). A 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-MeOTAD) being used widely to prepare highly efficient PSCs. However, Spiro-MeOTAD has some limitations due to its complex synthesis, which increases its cost, and it also requires dopants to improve its performance. Therefore, we designed thirteen unique small-molecule-based HTMs (MK1-MK13), which are easy to synthesize, highly cost-effective, and don’t require dopants to prepare efficient PSCs. Their electrical and optical properties are then investigated theoretically using advanced quantum chemical approaches. The designed molecules showed lower energy gaps and improved optical and optoelectronic characteristics because of the improved phase inversion geometry. The detailed photo-physical and optoelectronic characteristics have been studied using density functional theory (DFT) and time-dependent (TD-DFT) calculations. Moreover, we investigated the impact of holes and electrons and the density of states, open-circuit voltage, frontier molecular orbital, transition density matrix, and other structural and photovoltaic characteristics of these materials. Among these, the MK3 molecule possesses the much narrower optical band gap of 1.04 eV and absorbance (λ max) of 684 nm, respectively. In addition, a profound investigation of the MK3/PC61BM blend shows excellent charge transfer at the acceptor–donor interface. Therefore, our proposed technique is necessary for generating appropriate photovoltaic materials for efficient optoelectronic devices and is helpful in further advancing the field.

Can a bistable amphoteric native defect model explain the photo-induced transformation of MAPbI3 thin films?

Hybrid organic-inorganic perovskites such as MAPbI3 hold great promise for photovoltaic applications with power conversion efficiencies already exceeding 26 %. Despite the unprecedented advantages of these materials in photovoltaics and optoelectronics they exhibit a range of complex phenomena under light illumination that remain poorly understood. Here we use a combination of photoluminescence (PL) spectroscopy, cathodoluminescence imaging and theoretical calculations to correlate PL fluctuations in MAPbI3 thin films with changes in the spatial distribution and concentration of native defects. We demonstrate that short-term illumination results in a more homogeneous distribution of emitting and quenching sites, whereas prolonged illumination causes PL quenching. Our findings support the conclusion that the photo-induced transformation of MAPbI3 can be explained within a bistable amphoteric native defect model, wherein a neutral native defect can undergo a transition between a donor-like and acceptor-like configuration.

2D hybrid organic-inorganic perovskite displaying narrow-band violet-blue photoluminescence

Hybrid organic-inorganic perovskites represent a drastically expanding class of solid-state semiconducting materials for optoelectronics and photovoltaics. Thanks to the easy chemical tunability, this class of materials can offer emitters of very wide spectral range, however, violet-blue emitting hybrid perovskites still remain underrepresented. In this paper we report on a novel two-dimensional hybrid organic-inorganic perovskite (ethylammonium)2CdBr4. Crystal structure of the reported compound is composed of infinite inorganic 2D layers that are created by [CdBr6]4- octahedra connected in corner-by-corner manner. These layers are separated by organic ethyammonium cations which create hydrogen bonds with the inorganic part. Optical absorption measurements revealed the presence of a large band gap of 4.25 eV. Importantly, this material displays narrow photoluminescence band at 388 nm (full width at half maximum is 32 nm). Chromaticity coordinates of the perovskite emission are close to NTSC blue standard. Band structure and DOS calculations show that the states close to Fermi level predominantly originate from cadmium and bromide. Thus, here we offer a facile way towards violet-blue luminophore containing simple and widely available organic cation ethylammonium.

Reactive DC Sputtered TiO2 Electron Transport Layers for Cadmium‐Free Sb2Se3 Solar Cells

AbstractThe evolution of Sb2Se3 heterojunction devices away from CdS electron transport layers (ETL) to wide bandgap metal oxide alternatives is a critical target in the development of this emerging photovoltaic material. Metal oxide ETL/Sb2Se3 device performance has historically been limited by relatively low fill factors, despite offering clear advantages with regards to photocurrent collection. In this study, TiO2 ETLs are fabricated via direct current reactive sputtering and tested in complete Sb2Se3 devices. A strong correlation between TiO2 ETL processing conditions and the Sb2Se3 solar cell device response under forward bias conditions is observed and optimized. Numerical device models support experimental evidence of a spike‐like conduction band offset, which can be mediated, provided a sufficiently high conductivity and low interfacial defect density can be achieved in the TiO2 ETL. Ultimately, a SnO2:F/TiO2/Sb2Se3/P3HT/Au device with the reactively sputtered TiO2 ETL delivers an 8.12% power conversion efficiency (η), the highest TiO2/Sb2Se3 device reported to‐date. This is achieved by a substantial reduction in series resistance, driven by improved crystallinity of the reactively sputtered anatase‐TiO2 ETL, whilst maintaining almost maximum current collection for this device architecture.