Effect of Annealed and Non‐Annealed Inorganic MnS Hole‐Transport Layer for Efficient Sb₂(S,Se)₃ Solar Cells: A Theoretical Justification

Abstract

In solar-cell applications, metal chalcogenides have been widely used as light-harvesting materials, especially CIGS and CdTe solar cells, demonstrating a power conversion efficiency (PCE) of 23.35% [1] and over 22%. [2,3] Achieving net-zero carbon emission in the near future, and also due to the scarcity and toxicity of Ga and Cd, restricts further development. In recent years, the antimony chalcogenides family have been considered as a promising contender for absorber material, especially antimony selenide, Sb 2 Se 3 , antimony sulfur, Sb 2 S 3 , and antimony sulfoselenide, Sb 2 (S,Se) 3 . These materials show excellent photoelectric properties, such as tunable bandgap (1.1-1.7 eV), high-absorption coefficient (>10 5 cm À1 ), stability against moisture, as well as low toxicity, environmental friendliness, earth abundance, and finally, simple preparation process. [4][5][6][7][8][9][10] So far, the Sb 2 (S,Se) 3 solar-cell PCE has been quickly enhanced (i.e., over 10%) by material preparation, device configuration, defect passivation, and interface modification. [5,[11][12][13] And these devices are made up of an expensive organic Spiro-OMeTAD hole-transport layer (HTL), demonstrating poor device stability due to the bis(trifluoromethane) sulfonimide lithium salt (Li-TFSI) doping into Spiro-OMeTAD. Moreover, the toxicity of the dopant 4-tert-butylpyridine, additive acetonitrile, and the solvent chlorobenzene are hazardous to the human central nervous system. [6,14,15] It is well-known that the HTL plays a crucial role in determining the device's photovoltaic (PV) performance by extracting photogenerated holes from the absorber to the electrode and it's generating a built-in electric field at the rear interface. Therefore, choosing the HTL material with high hole mobility, high stability, low toxicity, and low cost is essential to enhance PV performance with improved device stability. According to the published reports, notably, the Tao Chen group employed different HTLs for Sb 2 (S,Se) 3 solar cells than conventional Spiro-OMeTAD, such as CsPbBr 3 perovskite quantum dots, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) doped copper phthalocyanine, and DTPThMe-ThTPA, demonstrating PCE 7.82%, [16] 8.57%, [17] and 9.7%, [18] respectively. However, the aforementioned HTLs are prepared by the solution process, which is unsuitable for large-scale productions. In that consideration, a thermally evaporated low-cost inorganic manganese sulfide (MnS) semiconductor is an excellent choice for the HTL, and recently, Qian et al. and Wang et al. used this MnS-HTL in Sb 2 (S,Se) 3 solar cells, achieving 9.6% [6] and 9.24% [19] of PCE. Also, their results evidently explain that the post-annealing treatment for MnS-HTL significantly influences the PV performance.

The impact of CBz-PAI interlayer in various HTL-based flexible perovskite solar cells: A drift-diffusion numerical study

“…6 a), whereas the FF also diminishes from 84 % to 69 % ( Fig. 6 d), similar to our previous reports [ 15 , 47 , 51 , 52 ]. Noticeably, V oc (1.32–1.24 V) and J sc (25.2–24.6 mA/cm 2 ) reduced a little while adjusting R S, whereas they remained unchanged while varying both R S and R sh .…”

Design and simulation of Cu2SnSe3-based solar cells using various hole transport layer (HTL) for performance efficiency above 32%

“…The results of our designed solar cells' PV capabilities in this section are displayed in figure 11 where T is temperature, M is the ideality factor, E a is the activa-tion energy for recombination, q is the elemental charge, k is the Boltzmann constant, J 00 is a prefactor, and J PD is photocurrent density. The plot of V oc against T in equation (5) should produce a straight line, and extrapolating this straight line to T = 0 K yields the activation energy (E a ), provided that M, J 00 , and J PD are temperature independent [78]. The main recombination mechanism in solar cells is typically interface-induced recombination, which typically occurs at the interfaces (ETL/absorber) or (absorber/HTL) if the E a is smaller than the absorber bandgap.…”

“…The main recombination mechanism in solar cells is typically interface-induced recombination, which typically occurs at the interfaces (ETL/absorber) or (absorber/HTL) if the E a is smaller than the absorber bandgap. In contrast, the Shockley-Read-Hall reaction takes place in the absorber's space charge region or neutral zone as the primary reaction in solar cells if the E a is close to or equal to the absorber bandgap [78]. E a may develop as a result of the extra activation energy that accounts for the effective density of states and the thermal velocity that is temperaturedependent [78].…”

“…In contrast, the Shockley-Read-Hall reaction takes place in the absorber's space charge region or neutral zone as the primary reaction in solar cells if the E a is close to or equal to the absorber bandgap [78]. E a may develop as a result of the extra activation energy that accounts for the effective density of states and the thermal velocity that is temperaturedependent [78]. The little increase in J SC is also a result of the band gap contracting as temperature rises.…”

Design and Simulation of CdS-Free Sb2(S, Se)3 Solar Cells with Efficiency Exceeding 20%

“…are promising materials for thin film solar cells, owing to their wide bandgap, physicochemical stability, and benign synthesis. However, the chemical incompatibility existing at the Sb 2 (S, Se) 3 /oxide interface induces the high density of undercoordinated/dangling bonds at the interface, which in turn accelerates the (trap-assisted) interface recombination, and contributes to a significant loss in the device performance (particularly in V oc ). ,− This chemical incompatibility has often been ignored in most of the simulation works on Sb 2 (S, Se) 3 PV and is the primary reason for the PCE values claimed by previous simulation works not aligning well with the experiments. − Bearing this fact in mind, we have restrained from using oxide-based ETL and HTL materials in this simulation work. ETL and HTL materials based on chalcogenides (e.g., ZnSe, MoS 2 , WS 2 , CuSbS 2 , and MnS), halides (e.g., CuI), or thiocyanates (e.g., CuSCN) coordinate strongly with Sb 2 (S, Se) 3 , facilitating an efficient charge transport across the Sb 2 (S, Se) 3 /ETL and Sb 2 (S, Se) 3 /HTL interfaces. ,− Recently, there has been growing interest and surge in experimental investigations to find alternatives for the CdS and Spiro-OMeTAD layer.…”