Inorganic Hole Transport Layer Research Articles

Co‐Solvent Assisted Optimization of the CuSCN Hole Transport Layer for Enhancing the Efficiency of Ambient Processable Perovskite Solar Cells with Carbon Counter Electrodes

In recent perovskite solar cell (PSC) research, copper(I) thiocyanate (CuSCN) is an emerging inorganic hole transport layer (HTL) due to its suitable band gap, matched band edge positions with the perovskite and high stability under ambient conditions. However, being a coordination polymer typically requires sulfide‐based solvents that strongly interact with Cu(I) for dissolution. Dipropyl sulfide (DPS) is generally used where it is very sparingly soluble of about 10–12 mg mL−1, which leads to low surface coverage with pin‐holes on the surface responsible for the generation of defects at the perovskite–HTL interface. In this study, addition of the optimized amount 100 μL of co‐solvent Acetonitrile (ACN) increased the CuSCN dissolution from 10 to 35 mg mL−1. ACN can act as a Lewis‐base making it capable of donating electrons to a Lewis‐acid like Cu+ from CuSCN. ACN is a polar aprotic solvent due to its highly polar CN bond and by adding CuSCN the dipole–dipole interactions can stabilize the CuSCN molecules in solution. The device with architecture (FTO/c‐TiO2/mp‐TiO2/MAPbI3/CuSCN/carbon) showed the higher power conversion efficiency (PCE) of ≈11% with Voc of 1.01 V and Isc 24.65 mA cm−2 showing excellent stability stored under ambient atmosphere which retains 80% of its initial efficiency after 10 days.

Bilateral Embedded Anchoring via Tailored Polymer Brush for Large-Area Air-processed Blue Light-Emitting Diodes.

Perovskite light-emitting diodes (PeLEDs) that can be air-processed promises the development of displaying optoelectronic device, while is challenged by technical difficulty on both the active layer and hole transport layer (HTL) caused by the unavoidable humidity interference. Here, we propose and validate that, planting the polymer brush with tailored functional groups in inorganic HTL, provides unique bilateral embedded anchoring that is capable of simultaneously addressing the n phases crystallization rates in the active layer as well as the deteriorated particulate surface defects in HTL. Exemplified by zwitterionic polyethyleneimine-sulfonate (PEIS) in present study, its implanting in NiOx HTL offers abundant nuclei sites of amino and sulfonate groups that balance the growth rate of different n phases in quasi-2D perovskite films. Moreover, the PEIS effectively nailed the interfacial contact between perovskite and NiOx, and reduced the particulate surface defects in HTL, leading to the enhanced PLQY and stability of large-area blue perovskite film in ambient air. By virtue of these merits, present work achieves the first demonstration of the air-processed blue PeLEDs in large emitting area of 1.0 cm2 with peak external quantum efficiency (EQE) of 2.09 %, which is comparable to the similar pure-bromide blue PeLEDs fabricated in glovebox.

Impact of Alternating-Current Operation on All-Inorganic Quantum Dot Light-Emitting Diodes.

In colloidal quantum dot light-emitting diodes (QD-LEDs), replacing organic hole transport layers (HTLs) with their inorganic counterparts is expected to yield distinct advantages due to their inherent material robustness. However, despite the promising characteristics of all-inorganic QD-LEDs, some challenges persist in achieving stable operation; for example, the electron overflow toward the inorganic HTL and charge accumulation within working devices return a temporal inconsistency in device characteristics. To address these challenges, we propose an operational approach that employs an alternating-current (AC) in all-inorganic QD-LEDs. We carry out comprehensive studies on the optoelectrical characteristics of all-inorganic QD-LEDs under direct-current (DC) or AC operation and demonstrate that AC operation can facilitate efficient charge carrier recombination within the QD emissive layer, leading to improved device efficiency and temporally invariant optoelectronic characteristics. Leveraging the intrinsic material robustness of inorganic charge transport layers (CTLs), our current study suggests a promising pathway toward enhancing the performance and stability of QD-LEDs, particularly for futuristic display applications.

Enhanced carbon-based back contact electrodes for perovskite solar cells: Effect of carbon paste composition on performance and stability

To address the issue of cost and instability in perovskite solar cells (PSCs), it is promising to substitute the regular hole collecting electrode i.e., spiro-OMeTAD/Au with inorganic hole transport layer (HTL)/carbon electrode. In this study, three carbon pastes were investigated with different binders: polymethyl methacrylate (PMMA), styrene-butadiene-styrene (SBS) and ethyl cellulose (EC). Carbon layers were compared in terms of mechanical stability, conductivity and performance as back contact electrodes in PSCs with an inorganic HTM composed of CuInS2 nanoparticles. To assess mechanical properties of the carbon pastes, adhesion tests by using tape, ultrasonication in the media of deionized water and acidic deionized water, and also flexibility test were performed. The carbon layer based on SBS carbon paste (SBS-CP) was intact after adhesion tests and over 1017 cycles of flexibility test. The one based on PMMA carbon paste (PMMA-CP) didn't tolerate all mechanical tests and disintegrated. The carbon layer based on EC carbon paste (EC-CP) partly damaged after adhesion tests and didn't pass the flexibility test. The best efficiency of 18.6 % was obtained for a device based on SBS-CP and significant shelf-life stability over 172 days stored in relative humidity of 40 % and dark.

Spin-coated high mobility MoO3 thin film for designing highly efficient lead-free perovskite solar cells

Among the thin film-photovoltaics, perovskite solar cells (PSCs) are one of the most developing topics of research in recent times. Research records reveal that around 26 % efficiency in PSCs has already been achieved so far. However, the commercialization of those PSCs is hindered due to the toxicity of lead (Pb), and the instability of organic cations as well as structural volatility. Several inorganic materials including inorganic hole transport layer (HTL) have recently been proposed and developed to reduce the organic part in the device structure. We fabricate MoO3 thin film materials and conduct a detailed study to realize the potential of MoO3 as a unique HTL for application in PSCs. The synthesis of MoO3 thin film includes several characterization techniques e.g. XRD, FESEM, EDX, UV–Vis, and Hall Effect measurement. We design a MoO3 thin film-based, lead-free PSC structure of FTO/MoO3/PTAA/(FA)2BiCuI6/ZnO/Ag and perform numerical analysis using the SCAPS-1D simulation tool. In the device simulation process, we use the experimentally obtained optoelectrical properties of the MoO3 film and achieve a maximum efficiency of around 22.28 % in a contained lead-free PSC.

All-Inorganic Hydrothermally Processed Semitransparent Sb2S3 Solar Cells with CuSCN as the Hole Transport Layer.

An inorganic wide-bandgap hole transport layer (HTL), copper(I) thiocyanate (CuSCN), is employed in inorganic planar hydrothermally deposited Sb2S3 solar cells. With excellent hole transport properties and uniform compact morphology, the solution-processed CuSCN layer suppresses the leakage current and improves charge selectivity in an n-i-p-type solar cell structure. The device without the HTL (FTO/CdS/Sb2S3/Au) delivers a modest power conversion efficiency (PCE) of 1.54%, which increases to 2.46% with the introduction of CuSCN (FTO/CdS/Sb2S3/CuSCN/Au). This PCE is a significant improvement compared with the previous reports of planar Sb2S3 solar cells employing CuSCN. CuSCN is therefore a promising alternative to expensive and inherently unstable organic HTLs. In addition, CuSCN makes an excellent optically transparent (with average transmittance >90% in the visible region) and shunt-blocking HTL layer in pinhole-prone ultrathin (<100 nm) semitransparent absorber layers grown by green and facile hydrothermal deposition. A semitransparent device is fabricated using an ultrathin Au layer (∼10 nm) with a PCE of 2.13% and an average visible transmittance of 13.7%.

Halogen doping of p-type inorganic hole transport layer: electronic nature-based dopant engineering for modulating hole selectivity in inverted planar perovskite solar cells

The role of metal cation and halide anion dopants in regulating the properties of NiOx hole transport layer (HTL) was explored. This study confirms that halide dopants also increase the Ni3+ defect density and work function of p-type inorganic HTL.

Influence of cobalt doping on structural and optical properties of copper oxide expected as an inorganic hole transport layer for perovskite solar cell

Influence of cobalt doping on structural and optical properties of copper oxide expected as an inorganic hole transport layer for perovskite solar cell

Charge-carrier engineering of staggered-gap p-CuAlO2/β-Ga2O3 bipolar heterojunction for self-powered photodetector with exceptional linear dynamic range and stability

Beta-gallium oxide (β-Ga2O3)-based heterojunction photodetectors (HJPDs) based on p-n heterojunction have drawn a lot of attention since p-type doping of β-Ga2O3 is challenging to perform. Thus, choosing affordable and effective inorganic hole transport layers (HTLs) is a crucial first step in commercializing PDs. Copper aluminum oxide (p-CuAlO2) is a very likely candidate material for heterojunction with β-Ga2O3, because of its large hole mobility for use in solar-blind photodetectors and high-power electronics. In this study, we propose employing a p-CuAlO2 interlayer for built a β-Ga2O3-based SBUV HJPDs by regulating the oxygen flow rate (OFR) from 0 % to 30 % using the RF magnetron sputtering (RFMS) technique. Prior to building the p-CuAlO2/β-Ga2O3 HJPDs, the heterojunction band alignment was established and displayed staggered-gap band alignment with a valence band (ΔEV) offset of 1.1 eV and conduction band offset (ΔEC) of 0.65 eV with OFR of 30 %. In response to the UV-C (255 nm) wavelength, the good optoelectronic device properties such as low dark current of ∼10−12 A, large photo-to-dark current (Ilight/Idark) ratio (∼104), responsivity (R) (26.36 mA/W), detectivity (D*) (2.87 × 1010 cmHz1/2W−1), external quantum efficiency (EQE) (1.28 × 104 %), noise-equivalent power (NEP) (0.03 pWHz−1/2), linear dynamic range (LDR) (99.13 dB), and comparable rise (τr) and decay times (τd) of 0.25 s and 0.15 s respectively, were demonstrated for p-CuAlO2/β-Ga2O3 HJPDs with OFR of 30 % and also compared with pristine Pt/β-Ga2O3 Schottky barrier diode photodetector (SBDPD). The band offset at the p-CuAlO2/β-Ga2O3 interface is employed to explain the improvement of p-CuAlO2/β-Ga2O3 HJPDs. The incorporation of p-CuAlO2 into Pt/β-Ga2O3 SBDPD lead to an improved extraction efficiency of the generated free hole carriers under illumination. The Silvaco TCAD simulator was employed to get insight into the function of the p-CuAlO2 layer. The investigation focused on analyzing the variation profile of the recombination rate and electric field in Pt/β-Ga2O3 SBDPD and p-CuAlO2/β-Ga2O3 HJPD with OFR of 30 %. The outcomes demonstrate the stability and electron transfer impact of staggered gap p-CuAlO2/β-Ga2O3 HJPDs. Our findings show that the p-CuAlO2/β-Ga2O3 HJPDs have a great deal of potential as a candidate structure for the Ga2O3-based modern optoelectronic technologies.

Toward Efficient and Fully Scalable Sputtered NiOx‐Based Inverted Perovskite Solar Modules via Co‐Ordinated Modification Strategies

Sputtered nickel oxide (NiOx) has become one of the most promising inorganic hole transport layers for p–i–n perovskite solar cells (PSCs) due to its appealing features such as its robust nature, low material cost, and easy integration to tandem structures and large‐area applications. However, the main drawback with NiOx‐based PSCs is typically low open‐circuit voltage (VOC) due to the inferior energy‐level alignment, low charge mobility, and high recombination at the interface. Herein, two types of phosphonic acid self‐assembled monolayers (SAMs) deposited by blade coating as an interfacial layer to modulate the sputtered NiOx/perovskite interface properties are used. While sputtered NiOx serves as a conformally coated hole selective layer, the ultrathin SAM interlayer facilitates the hole extraction and minimizes the energy loss at the interface. Co‐ordinately introduced stabilizing additive, namely octadecyl 3‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)propionate (I‐76), further improves the device performance of NiOx/SAM‐based PSCs, resulting in VOC of 1.14 V and a power conversion efficiency of 21.8%. By applying these strategies for perovskite module upscaling, aperture area module efficiencies of 19.7%, 17.5%, and 15.5% for perovskite minimodules of 4, 16, and 100 cm2 are demonstrated, corresponding to active area module efficiencies of 20.4%, 18.0%, and 16.4%, respectively.

Enhancement in Efficiency of Methyl Ammonium Tin Iodide-Based Perovskite Solar Cell Using SCAPS-1D

Perovskite solar cells came to limelight owing to their simple fabrication processes, cost-effectiveness, better optoelectronic characteristics and outstanding power conversion efficiencies (PCEs). These solar cells have simply outpaced their rival cells since the alteration from aqueous hole transport layers (HTLs) to solid HTLs. Various layers of a perovskite cell viz. light absorber layer, electron transport layer (ETL) and HTL play a decisive role in ascertaining its performance. Today, various types of organic and inorganic HTLs are available but inorganic HTLs have gained an upper hand over their organic counterparts in terms of stability, cost, fabrication and material properties which represent them as a prospective candidate for optimum perovskite device. Copper antimony sulfide (CuSbS[Formula: see text] is a common HTL available in abundance with the benefit of an adequate bandwidth of 1.54[Formula: see text]eV. In addition, CuSbS2 possesses substantial band aligning and electron inhibiting features. This research paper elaborates a relative study of two perovskite solar devices possessing discrete inorganic hole transport layers, i.e., cuprous iodide (CuI) and copper antimony sulfide (CuSbS[Formula: see text], and discrete perovskite layers, i.e., MAPbI[Formula: see text]Cl[Formula: see text] and MASnI3, using the same negative charge transport layer, i.e., Cd[Formula: see text]Zn[Formula: see text]S, through numerical simulation employing SCAPS-1D. The effects of thickness, defect density and doping concentration with respect to absorbing layer on the efficiency and other parameters of perovskite layers are also discussed. By employing CuSbS2 with MASnI3 in the proposed device, the solar cell parameters are efficacious enough demonstrating the [Formula: see text] of 1.10[Formula: see text]V, PCE of 31.11%, fill factor (FF) of 83.05% and [Formula: see text] of 33.75[Formula: see text]mA[Formula: see text]⋅[Formula: see text]cm[Formula: see text].

An Experimental and Simulation Study of Cu6BiAgI10 Photovoltaics with Various Organic and Inorganic Hole Transport Layers for the Improved Photovoltaic Performance of Solar Cells

An Experimental and Simulation Study of Cu₆BiAgI₁₀ Photovoltaics with Various Organic and Inorganic Hole Transport Layers for the Improved Photovoltaic Performance of Solar Cells

Stability and Efficiency Enhancement of Antimony Selenosulfide Solar Cells with Inorganic SnS‐Modified Nickel Oxide Hole Transport Materials

Antimony selenosulfide (Sb2(S,Se)3) has been emerging as a promising light absorber owing to its tunable bandgap (1.1–1.7 eV), high absorption coefficient (&gt;105 cm−1), and excellent phase and environmental stability. Lithium salt‐doped 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxy‐phenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) has been generally used as the hole transport layer (HTL) in these high‐efficiency antimony selenosulfide solar cells so far. However, the lithium‐ion reactions and migration in this HTL may cause serious challenges for the stability of these solar cells. Herein, stable and low‐cost tin monosulfide (SnS) nanoparticles surface‐modified nickel oxide (NiOx) as an inorganic hole transport layer to fabricate highly efficient and stable all‐inorganic solar cells is developed. It is found that NiOx films not only demonstrate a higher conductivity but also form better energy band alignment after SnS surface treatment. Consequently, the power conversion efficiency of the full inorganic Sb2(S,Se)3 solar cells increases from 4.85% to 6.41%. Most importantly, the devices also demonstrate much improved thermal, moisture, and long‐term stabilities as compared to the solar cells with spiro‐OMeTAD hole transport layer.

Low-Cost Layered Double Hydroxides as Inorganic Hole Transport Layer for Perovskite Solar Cells

Low-Cost Layered Double Hydroxides as Inorganic Hole Transport Layer for Perovskite Solar Cells

Device modelling and optimization of various n-i-p configurations for MASnI3 perovskite solar cells to achieve high efficiency using Solar Cell Capacitance Simulator-1D

Perovskite materials are potential light harvesters, and in specific tin-based absorbers such as methyl ammonium tin iodide (MASnI3) are non-toxic with distinguished optoelectronic properties. This is the first simulation report to explore the application of strontium titanate (SrTiO3) as an electron transport layer (ETL) in planar n-i-p MASnI3 perovskite solar cell (PSC) device. In an attempt to enhance the output performance of MASnI3 PSCs, a systematic approach is devised to determine appropriate alternative charge-selective materials via solar cell capacitance simulator (SCAPS-1D) software. The significance of varying thickness, donor doping concentration, acceptor doping concentration, defect density, diffusion length, and energy band offset for the reference PSC configuration TiO2/MASnI3/Spiro-OMeTAD are investigated. The optimized reference structure delivered 19.72% efficiency. In pursuit of high photovoltaic performance, seven different electron transport materials were comparatively examined. As a result, PCBM, In2S3, and CeO2 were considered not suitable due to their limited electrical performance. Consequently, seven inorganic hole transport layers (HTL) along with four suitable ETL were utilized in MASnI3 PSC to construct twenty-eight novel n-i-p device structures whose efficiency ranges between 14.20% and 22.77% respectively. The influence of varying the work function of back contact, series resistance, shunt resistance, and temperature on the photovoltaic parameters was analysed. The vital parameters investigated in this simulation for implementing state-of-the-art PCS are energy band offset, diffusion length, activation energy, recombination current profile, and built-in-potential. The device configuration featured with SrTiO3/MASnI3/CuO and SrTiO3/MASnI3/MASnBr3 achieved a maximum efficiency of 22.77% and 22.60%, respectively. The PSC tailored with SrTiO3 have better thermal stability and enhanced fill factor, which accounts for improving the output power. These novel findings of all-inorganic PSC will provide preliminary support for practical implementation.

Modeling and simulation of > 19% highly efficient PbS colloidal quantum dot solar cell: A step towards unleashing the prospect of quantum dot absorber

We used the SCAPS-1D simulation tool to maximize the performance of lead sulfide (PbS) solar cells. A PbS solar cell was first modeled and then experimentally verified from past research. The ZnO electron-transport layer (ETL) was then replaced with ZnO:Al ETL material. Additionally, the fluorine-doped tin oxide work function, PbS-TBAI, ZnO:Al layer thicknesses, ZnO:Al/PbS-TBAI, PbS-TBAI/PbS-EDT defect density, PbS-TBAI defect density, ZnO:Al, and PbS-TBAI doping concentration were optimized. Results showed a greater alignment of the absorber-layer valence band with the HOMO and LUMO of ZnO:Al than that of ZnO ETL. The PbS solar cell exhibited the greatest efficiency at the optimum values of 0.4 µm, 0.04 µm, 1019 cm–3, 4.0 eV, 1017 cm–3, 1014 cm–2, 1018 cm–2, and 3.8 eV for absorber thickness, ETL thickness, ETL doping concentration, work function of front contact, PbS-TBAI doping concentration, and electron affinity of ZnO:Al, respectively. The PbS solar cell also performed best at interface defect densities of 1014 and 1018 cm–2 for ZnO:Al/PbS-TBAI and PbS-TBAI/PbS-EDT, respectively. The PCE of ZnO:Al ETL-based device also increased from 15.036% before optimization to 19.169% after. The optimized result was found to be affected by temperature. The PbS-optimized device with inorganic hole-transport layers (HTLs) demonstrated higher performance than the device with organic HTL. This finding was attributed to the low hole mobility in the organic HTL than those of inorganic ones. Therefore, the ZnO:Al ETL-based device was more efficient than the ordinary ZnO ETL-based device.

Exploring the performance of perovskite solar cells with dual hole transport layers via SCAPS-1D simulation

The potential of perovskite solar cells (PSCs) to produce high efficiency (over 25 %) is well known, but the poor stability of these solar cells is still a concern for practical applications. Thus, improving the stability is essential for furthering the development of PSCs. To address this issue, researchers found that incorporating inorganic materials into the hole transport layers (HTLs) can improve the stability of PSCs, yet charge recombination at the interface between the perovskite and inorganic HTLs can still reduce the efficiency of the PSCs. This study simulated the performance and mechanism of methyl ammonium lead iodide (MAPbI3) PSCs with a dual HTL using Solar Cell Capacitance Simulator-one Dimension (SCAPS-1D). A dual HTL formed by combining Spiro-OMeTAD (spiro), a highly efficient hole transport material, and copper zinc tin sulfide (CZTS), a highly stable hole transport material, leads to a PSC with a power conversion efficiency (PCE) of 23.47 % and significantly improved stability. Simulation results of the electric field at the interfaces of PSCs indicated that the PSC with spiro/CZTS as dual HTL have enhanced charge separation and reduced recombination. Furthermore, the simulation results have also revealed the influence of different parameters, such as absorber thickness, absorber defect density, HTL thickness, HTL/absorber interface defects, temperature, series resistance, and shunt resistance, on solar cell’s characteristics.

Seed‐Assisted Cu‐Doped Chemical Bath Deposition for Preparing High‐Quality NiOx Hole‐Transport Layers in Perovskite Solar Cells

P‐type NiOx films are widely used as hole‐transport layers (HTLs) in p–i–n perovskite solar cells (PSCs) owing to their wide bandgap, stability, and optical transmittance. Chemical bath deposition (CBD) is an effective method for growing metal oxide HTLs. However, NiOx films prepared by the CBD method have pinholes because of their small grain size, which makes it difficult to cover the substrate in all directions, leading to severe carrier recombination at the interface between NiOx and perovskite. Herein, the device efficiency is improved from 18.13% to 22.51% using NiOx prepared by CBD with seed‐assisted growth and Cu‐ion doping as the HTL. The addition of crystal seeds significantly enhances the grain size, resulting in better substrate coverage by the prepared NiOx films. Cu‐ion doping improves the conductivity of the film and enhances its ability to extract holes. In addition, the results confirm that this method is suitable for the manufacturing of large‐area modules and has good reproducibility. This research demonstrates an effective CBD method for creating NiOx films for use in PSCs and offers a new approach for preparing inorganic HTLs using CBD.

Growth and Exploration of Inorganic Semiconductor Electron and Hole Transport Layers for Low-Cost Perovskite Solar Cells

The perovskite exhibited outstanding performance and was a promising alternative material for a low-cost, high power conversion efficiency (PCE) solar cell application. To avoid the high-cost organic materials as electron transport layers (ETL) and hole transport layers (HTL) in perovskite solar cells (PSCs), here introduce the inorganic semiconductor nanomaterials ZnS and CuS work as an ETL and HTL, respectively. In this work, we selected chalcogenides such as zinc sulfide (ZnS) and copper sulfide (CuS) as the 2-electron and hole transport layers and utilized them for perovskite solar cell application. For the proposed cell structure FTO/ZnS/perovskite (CH3NH3PbI3)/CuS/Ag, the deposition of layers has been achieved via different techniques such as thermal evaporation, spin coating and doctor blade, respectively. X-ray diffraction and Field effect scanning electron microscopy (FESEM) with Energy-dispersive X-ray spectroscopy were used to characterize the structural and morphological properties of the prepared samples. UV-Visible spectrophotometer and current density-voltage curve were used to measure the optical and electrical parameters of the deposited layers, respectively. From the J-V characteristics, for the proposed and fabricated PSCs, the estimated PCE is about 0.28 %, open-circuit voltage (VOC) = 0.29 V, and short-circuit current density (JSC) = 3.96 mA/cm2. The results are good and the inorganic nanomaterial layers used in this study are promising for future studies. HIGHLIGHTS In this study, chalcogenide materials such as zinc sulphide (ZnS) as the electron transport layer and cadmium sulfide (CdS) as the hole transport layer in solar perovskite cell applications were investigated Use easy and simple deposit methods such as chemical bath deposition and doctor blade method The possibility of using chalcogenide materials in the field of perovskite solar cells, although the efficiency of the obtained cell is very small, is an indication of the response of such materials in the application of perovskite solar cells GRAPHICAL ABSTRACT

The Effect of Different Precursor Solutions on the Structural, Morphological, and Optical Properties of Nickel Oxide as an Efficient Hole Transport Layer for Perovskite Solar Cells

Perovskite solar cell (PSC) technologies have recently become a popular research topic. The hole transport layers (HTL) are important in establishing stable and efficient PSC by regulating charge absorption, interlayer recombination losses, and band alignment. Spiro-OMeTAD was extensively used as the HTL to fabricate highly efficient PSCs. Despite Spiro-OMeTAD having the benefit of providing high PCEs, it is costly, hazardous to the ecology, and cannot provide high efficiencies in the lack of additional additives that can reduce their stabilities. Inorganic HTL, specifically nickel oxide (NiO), has garnered much interest due to its low-cost, enhanced mobility, and strong stability to attain high efficiency. This study investigated different precursor solutions of NiO synthesis (Method I, II, and III) and deposited using the spin coating approach. The films were annealed at different annealing temperatures (400°C, 550°C, and 700°C) and evaluated by X-ray powder diffraction (XRD), UV-Vis spectroscopy, and Scanning electron microscopy (SEM) to test their structural, morphological, and optical characteristics, respectively. The findings of XRD revealed that a higher annealing temperature increases the crystallite size and decreases the microstrain through the study from Scherrer’s and Williamson-Hall’s (WH) equations. From the SEM analysis, the films show uniformity, large crystals, and agglomeration of particles. The annealing temperature from 400°C to 700°C reduced bandgap energy from 3.6 eV to 2.1 eV. According to the result, NiO produced at an annealing temperature of 700°C (Method I) exhibited the best characteristics and might be a viable option for HTL in PSCs.