Charge-carrier recombination within the photoactive and charge extraction layers is one of the major obstacles to achieve high performance perovskite solar cells. Here, we demonstrate an ultrathin layer of ZnOS in between SnO2 and halide perovskite film that can effectively passivate the defects, suppressing the nonradiative recombination loss. It also helps to moderate the perovskite layer with increasing surface potential, which facilitates transferring the carriers from the perovskite to the hole transport layer, consequently providing an understanding of the bottom-up interfacial passivation of perovskite films. An enhancement of V OC ∼ 100 mV mainly causes the efficiency improvement from 17.22 to 19.4% in the combined SnO2–ZnOS based solar cell. In addition, we have performed a device modeling and theoretical analysis of these perovskite solar cells with and without the passivation layer. Theoretical results for the electronic band structure indicate that ZnOS contains an intermediate band structure between SnO2 and perovskite resulting in a much better band bending for the SnO2–ZnOS based solar cells. It is observed that the numerical results are in good agreement with the experimental outcomes. The combined electron transport layer strategy provides a way for defect passivation for further efficiency enhancement of the perovskite solar cells through interface engineering.

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In this article, we have systematically investigated the structural, electronic, optical and thermoelectric properties of Rb2Ag(Ga/In)Br6. The resulting negative formation energy along with the absence of imaginary phonon modes confirm the thermodynamic stability of Rb2Ag(Ga/In)Br6. In addition, the derived electronic properties by using GGA‐PBE + mBJ + SOC functional show that the direct band gap values are 1.21 eV and 1.42 eV for Rb2AgGaBr6 and Rb2AgInBr6, respectively. Furthermore, the dispersed direct band nature of Rb2Ag(Ga/In)Br6 leads to their outshining optical properties such as higher order (105 cm−1) absorption coefficient, appreciable optical conductivity, and low reflectivity. Moreover, the higher figure of merit values of Rb2Ag(Ga/In)Br6 are resulted from their ultra‐low thermal conductivity and high electrical conductivity. Thus, Rb2Ag(Ga/In)Br6 are predicted to be potential photovoltaic and thermoelectric materials.

Summary In this article, we have systematically investigated the structural, electronic, optical, and thermoelectric properties of Cs2Tl(As/Sb)I6. The obtained negative formation energy along without the presence of imaginary phonon frequency confirmed the thermodynamic stability of Cs2Tl(As/Sb)I6. In addition, the new mBJ approach showed the direct band gap value of 1.10 and 1.33 eV for Cs2TlAsI6 and Cs2TlSbI6, respectively. Furthermore, the dispersed direct band nature of Cs2Tl(As/Sb)I6 leads to their outshining optical properties such as higher‐order (105 cm−1) absorption coefficient, appreciable optical conductivity, and low reflectivity. Moreover, the higher figure of merit values of Cs2Tl(As/Sb)I6 are resulted from their ultra‐low thermal conductivity and high electrical conductivity. Thus, Cs2Tl(As/Sb)I6 are predicted to be potential photovoltaic and thermoelectric materials.