Energy is essential to life, yet the world has been in the midst of an energy crisis due to the tremendous demand for it [1]. Using renewable energy sources is one way to address the pressing need for clean power on a worldwide scale. Because of the urgent need for low-cost and reliable energy sources, researchers have focused on developing cheaper and more efficient solar cells [2]. Solar energy has the greatest potential to address the problems caused by ecologically problematic energy sources like fossil fuels since it is the most abundant, accessible, and environmentally benign kind of energy [3]. The first solar cell was discovered in the nineteenth century for converting sunlight into electrical energy via the photovoltaic effect. Solar cells are classified into three types: silicon-based solar cells, organic solar cells (OSC), perovskite solar cells, hybrid, and dye-sensitized solar cells (DSSC). These cells work on three principles: charge production (exciton) by photon absorption, charge separation as well as transfer to respective electrodes [4,5].

Energy needs may perhaps be met by solar cells alone, making them the most promising renewable energy source. Poor efficiency, high cost, and inflexible architecture ensured that while inorganic silicon-based solar cells were the most ecologically benign and thermally stable, their uses were restricted [6]. Organic photovoltaics (OPV) have attracted the attention of scientists because of their unique properties, which make them more desirable than inorganic solar cells [7]. OSC has exceptional optoelectronic characteristics because of its enhanced shape and intense light absorption. Manufacturing of single-layered OSC has raised operational efficiency by 15% and creating donor-acceptor mixed layered OSC has also increased solar cell efficiency [8]. Manufacturing bulk heterojunction (BHJ) OSCs from polymers and fullerenes allowed engineers to solve the power outage problem at a reasonable cost [9]. In addition, replacing fullerene with non-fullerene in BHJ OSC has been shown to increase efficiency by 6% [10]. The use of fullerene and its analogues in the development of solar cells resulted in an 11% rise in power conversion efficiency. Reduced fullerene consumption in the OSC was the result of reduced photochemical effectiveness and a compact structure that is difficult to change [11,12].

In addition, the low efficiency of organic solar cells in compared to inorganic-based systems is a major downside. Organic semiconductors are preferable to inorganic semiconductors because their band gap is significantly larger [2]. As a result of its advantageous photophysical properties, high operational efficiency, and low-cost assembly techniques, perovskites solar cells (PSCs) have recently attracted a lot of attention from both academics and businesses [[3], [4], [13]].

Hole-transporting layers (HTLs) are critical in perovskite solar cells (PSCs) for hole absorption and transport, system stability, and cost. Finding efficient, dependable, transparent, and cost-effective HTLs is critical for moving PSCs closer to commercialization. Organic HTLs offer several advantages over inorganic HTLs, including a tunable bandgap and energy level, easy production and refining, solution processability, and a net cheap price [[6], [7], [14], [15]].

Because of its cheaper cost and equivalent photovoltaic performance, ACR-TPA may be a potential alternative to spiro-MeOTAD. As a result, the current initiative's ACR-TPA-based reference has been fundamentally updated. ACR is a common building piece in the field of thermally activated delayed fluorescence for organic light-emitting diodes [8,9]. However, the emission characteristics of ACR-based small molecules are not relevant to this investigation, however ACR is optimal for the perovskite solar cell usage [[10], [11], [12], [16]]. In terms of structure, the sp3 carbon atom in the 9th position in ACR has two methyl groups for solubility in typical organic solvents. Because of the presence of C and N atoms at the 9th and 10th positions between the two phenyl rings, respectively, the delocalization of π-electrons between adjacent phenyl units is limited, allowing for low lying highest occupied molecular orbital (HOMO) energy levels and significant oxidative stability. TPA groups guarantee that the overall molecular structure has a good hole carrying nature while also extending the conjugation. Furthermore, the insertion of the five methoxy (OMe) groups at the outer locations of ACR-TPA is expected to have a good influence on the electrical characteristics and act as effective stabilizers for the perovskite/HTM junction [10,[17], [18], [19]].

In current study, previously manufactured Acridine (ACR) and triphenylamine (TPA) based ACR-TPA was used as a reference (ACR-TPA-R) to inform the design of five small donor molecules (ACR-TPA-X1, ACR-TPA-X2, ACR-TPA-X3, ACR-TPA-X4, ACR-TPA-X5) by replacing the model's methoxy group on both sides with various thiophene bridged acceptor functionalities (see Fig. 1). Acceptors comprising cyano, sulphur, oxygen, nitrogen, fluorine, and carbonyl in addition to thiophene have been included into the ACR-TPA-R conjugated architecture, which has resulted in a change in the structure and optoelectronic properties of the compound. Narrowing the bandgap, increasing molecular conjugation, and shifting absorption to longer wavelengths can be achieved by adding cyano, sulphur, oxygen, nitrogen, fluorine, or carbonyl groups to the conjugated framework of a molecule [20]. This research delves deeply into a wide range of promising small donor chemical development approaches for potent OSCs and beneficial HTMs for PSCs. The combination of these compounds, which have similar optical properties but different molecular structures, improves device performance.