Organic-inorganic perovskite structure-based (OIPSB) solar cells: A progress from invention

The organic-inorganic perovskite structure-based (OIPSB) materials are key material for optoelectronic industry. In this review paper, we have discussed some physical properties of OIPSB compounds (lead-based) which we got from previous research findings. The main compounds of OIPSB have been given with their electronic and optical properties. Furthermore, their applications are discussed in solar cells with device structures. A full mini review of organic-inorganic perovskite solar cells (OIPSCs) is given from its initial Power conversion efficiency (PCE) <4% to highest PCE of > 24%.

The number of OIPSB compounds has been developed, the organic-inorganic lead halides (CH3NH3PbX3) where (X=Cl, Br, I) and organic-inorganic tin halides (CH3NH3SnX3) where (X=Cl, Br, I) with their blend structures using different techniques.Among all these compounds the OIPSB CH3NH3PbI3 Shows exceptional character in solar cells as radiation absorber which crossed PCE of 24% [10].The verified efficiency is available at National Renewable Energy Laboratory (NREL) efficiency chart [11].The easy processing, cost effectiveness and natural abundancy make this material beyond solar cells devices such as water splitting [12], light emitting diodes [13,14] and lasers [15][16][17][18][19].
Recently we used DFT approach to investigate electronic and optical properties of all lead-based OIPSB compounds (CH3NH3PbX3) where (X=Cl, Br, I) and found that CH3NH3PbI3 has narrow band gap as compared to CH3NH3PbCl3 and CH3NH3PbBr3 compounds.The direct band gap of CH3NH3PbI3 is found to be 1.9 eV and optical absorption α (ω) is 4283.20 at 3.18 eV which is quite impressive compared with silicon [20].The absorption spectra increase in visible range and reduces after 3.2 eV and make some ups and down due to multi-elements in of CH3NH3PbI3 compound.The Optical conductivity σ (ω) is 69.071 cm -1 at 372 nm (3.34 eV) determined by GGA.The valence band and conduction bands are mostly occupied by halides and lead orbitals respectively.The overall CH3NH3PbI3 is most suitable material for organic solar cells device [21].
In this review we have given the details of mainly CH3NH3PbI3-based solar cells progress based on PCE and device configuration.The review is taken from 2009 since first organic-inorganic hybrid solar cells discovered.# )6, ;<:=+<=:-; 7. ) *4 * *4 + * , *;7:8<176 +7-..1+1-6< )6, -78<1+)4 +76,=+<1>1<@ 7. *& !!!! The OIPSB solar cells Perovskite solar cells are a type of solar cell that use a material called perovskite as the light-absorbing layer.The OIPSB solar cells have attracted significant attention due to their high efficiency, low-cost, and easy-processing features.In recent years, significant progress has been made in the development of OIPSB solar cells.The efficiency of these cells has increased rapidly, with some research groups reporting efficiencies above 24%.This is a significant improvement over the initial efficiencies of around 4% that were reported when OIPSB solar cells were first developed in 2009 [1].
In 2009, the first OIPSB solar cells was introduced by kojima and workers.They used CH3NH3PbI3 and CH3NH3PbBr3 as sensitizer in dye-sensitized solar cell (DSSC) which shown PCE of 3.81 % and 3.13 % respectively.The CH3NH3PbI3-based solar cells shown high PCE while high voltage 0.96 V was obtained using CH3NH3PbBr3-based solar cells.Structurally, they coated N-type semiconductor TiO2 nanocrystalline paste on fluorine-doped SnO2 transparent glass (FTO, Nippon Sheet Glass 10 Ω/sq).The thickness of TiO2 was kept 8-12 μm using screen printers and sintering at temperature of 480 °C for 1 hour in air.The nanocrystalline particles of CH3NH3PbX3 (X = Br, I) were deposited by self-organization process which started with precursor solution having stoichiometric amounts of PbX2 and CH3NH3X.The film formation of CH3NH3PbX3 on TiO2 was done by spin-coating and X-ray diffraction (XRD) analysis also confirmed that films formation on TiO2 of both OIPSB compounds are crystalline in nature as well as perovskite structure formation.Finally, the common device configuration was as FTO/TiO2/CH3NH3PbX3, (X = Br, I) for first OIPSB solar cells.The short-circuit photocurrent densities Jsc (mA/cm 2 ) and fil factor are 11.0, 5.57 and 0.59, 0.57 for CH3NH3PbI3 and CH3NH3PbBr3 respectively [1].
After two years, in 2011 Jeong Hyeok Im et .alprepared efficient quantum dots sensitized solar cell with 2-3 nm CH3NH3PbI3 nanocrystal as light absorber layer.The achieved PCE of 6.54% with Voc of 0.605, ff = 0.513 and Jsc = 13.31.The device architecture is as follows; FTO/TiO2/ CH3NH3PbI3.The FTO was washed with ethanol using ultrasonic bath for 20 mints and heated at 500 °C continuously for 15 mints.After that, TiO2 particles having size of 20 nm are deposited on FTO substrate and again heated to 1 h at 550 °C.After that, the perovskite solution was spread on TiO2 film and keep it for 1 min so that it penetrates in film and then spun it for 40 s at 2000 rpm (round per minute) in ambient atmosphere.Finally, the last perovskite layer was dried for 30 mints at temperature ranges from 40-160 °C [2].
After that in 2012, Hui Seon Kim et .alreport solid state mesoscopic heterojunction organic-inorganic solar cells having CH3NH3PbI3 nanoparticles.The achieved PCE of 9.7 % with Voc = 0.88 V, ff = 0.62 and Jsc = 17.6 mA/cm 2 when exposed to sun light.The device configuration is as FTO/TiO2+spiro-MeOTAD/(CH3NH3)PbI3.The pores of submicron TiO2 film was filled by spiro-MeOTAD which acts as hole conductor.So, introducing hole conductor in OIP solar cells configuration increased the PCE as well as device stability as compared to solution based-cells [3].At the same year, Michael M. Lee with coworkers fabricated cost-effective solution-processable highly efficient solar cells using highly crystalline CH3NH3PbI3 material as light absorber.They achieved PCE of 10.9 % when exposed to light with Voc = 0.98 V, Jsc = 17.8 mA/cm 2 and ff = 0.63. the device configuration was FTO/TiO2+Al2O3/CH3NH3PbI3/spiro-MeOTAD/ and with outer Ag layer as electrode.This mesosuperstructured solar cells containing additional mesoporous alumina contains few energy losses as compared with previous fabricated OIPSB solar cells.By using mesoporous alumina in TiO2 layer enhanced the electron transportation through CH3NH3PbI3 absorber towards electrode [4].
Just after one year, Jun Hong Noh et .al in 2013 fabricated more efficient, low cost and more stable nano-structures solar cells by using CH3NH3Pb(I1−xBrx)3 as light absorber.They used bi-layers (bl) and additional polymer polytriarylamine (PTAA) to enhance the efficiency and stability of OIPSB solar cells.The device PCE approached to 12.3 % with Jsc = 18 mA/cm 2 , Voc = 1.13 V and ff = 0.74.The device architecture was as FTO/bl-TiO2/TiO2+ CH3NH3Pb(I1−xBrx)3/PTAA with electrode Au for charge transportation at outer end.The TiO2 and PTAA in device fabrication enhanced the hole transferred ratio towards electrode when it was illuminated in sun light, hence acts as hole transport material (HTM) [5].
In the same year, Mingzhen Liu and his team introduced a simpler planer hetrojunction solar cells with improved PCE and demonstrated that nanostructering is not necessary for getting high efficiency.They used physical vapor deposition method (PVD) for coating organic-inorganic layer and achieved PCE of 15.4 % with Jsc = 21.5 mA/cm 2 , Voc = 1.07 V and ff = 0.67.They used the simplest architecture as FTO/compact TiO2/CH3NH3PbI3-xClx/ spiro-MeOTAD with Ag electrode at the end.The formation of TIO2 layers was done by spin coating and organic-inorganic materials are coated by PVD method with organic CH3NH3I and inorganic PbClx separate targets on compact TiO2 layer at 1025 mbar.Finally, the device was capped by silver Ag metal electrods using thermal evaporation method at 1026 mbar [6].
Just after one year, Nam Joong Jeon et .aland his team-mates developed efficient OIPSB solar by solution-based spin coating method and achieved 15.8 % PCE.The measured optical parameters Jsc, Voc and ff were measured as 19.9 mA/cm 2 , 1.06 V and 0.75 respectively.The device architecture follows the pattern as FTO/bl-TiO2/Perovskite+TiO2/Perovskite/PTAA and Au as electrode capped on device.The polytriarylamine (PTAA) acts as HTM which improved hole conductivity of OIPSB solar cells.The absorbers layers consist of two parts, the mixture of TiO2 and CH3NH3PbI3 and upper layer of CH3NH3PbI3 without TiO2.Finally, a better solar cell with improved photovoltaic properties were fabricated with simplest processing techniques.The figure (4) shows the architecture and properties of OIPSB solar cells architecture with XRD pattern of annealed perovskite film (at 100 °C) and formation procedures [7].Moreover, in 2017 Seong Sik Shin et .alfabricated the OIPSB solar cells with much improved PCE of 21.2 %.They used lanthanum-doped BaSnO3 (LBTO) layer on FTO to enhance electronic mobility and stability of OIPSB solar cells.The device architecture was FTO/LBSO/CH3NH3PbI3/PTAA with outer Au electrode encamped.The value of Jsc, ff, and Voc was 23.4 mA/cm2, 81.3% and 1.12 respectively when exposed to light.Finally, the device stability was checked and up to 42 days (1000 h) the OIPSB solar cells retain 93 % of its initial performance when fabricated [22,9].Finally, in 2022 Hang Li and coworker reported 24.2 % PCE using formamidinium iodide (FAI), cesium iodide (CsI), lead iodide (PbI2) and lead chloride (PbCl2).They used evaporation deposition method to fabricate solar cells with improved efficiency.The device architecture as FTO/FAI/Cs0.05PbI2.05-xClxwith Jsc = 25.91 mA/cm 2 , ff = 80.99 and Voc = 1.145V.The FAI film first deposited on FTO substrate and then individual PbCl2, PbI2 and CsI targets are deposited using vacuum evaporation method.These solar cells shown outstanding performance and highest stability when exposed to light.The solar cells were tested for 4000 h in air and shown negligible decline in performance, hence very effective solar cells for future commercialization [10].

Conclusion of work
The OIPSB solar cells attracted the photovoltaic community because of excellent power conversion efficiency (PCE).The PCE is exceeded from 20% in a single decade with device structure and manufacturing method.The OIPSB solar cells can be manufacturing by spin-coating, solution method or by physical vapor deposition.In all methods, solution method is most easy method for manufacturing OIPSB solar cells.Furthermore, it is clear from the review that PCE depends on both device structure and other transport material like, ETL, HTL and electrodes.

Figure. 5 .
Figure. 5.The OIPSB solar cells (a) formation process, (b) layers 3-D design, (c) X-ray diffraction peaks and (d) SEM image from side for better understanding of device architecture.After that, Zhou, H et al manufactured OIPSB solar cells with much improved PCE of 19.3 % with solution method at low temperature of less than 150 C.They used CH3NH3PbI3-xClx as light absorber with spiro-MeOTAD as light absorbing material and indium Titanium oxide (ITO) with polyethyleneimine ethoxylated (PEIE) as electrode instead of FTO that reduced work function.Additionally, Yttrium-doped TiO2 (Y-TiO2) was used as electron transport material to enhance charge extraction from absorber.The

Figure 6 .
Figure 6.(a) SEM image from side and (b) different layers general designs with electronic band gapes.

Figure 7 .
Figure 7. (a) SEM cross-sectional image of OIPSB solar cell, (b) J-V curves, (c) external quantum efficiency (EQE) spectrum and Jsc of OIPSB solar cells and (d) the Histograms of PCEs taken from a photocurrent density stabilized at the maximum power point during 100 s [9].