Gaurav Kapil1,2,Takeru Bessho2,Qing Shen1,Hiroshi Segawa2,Shuzi Hayase1
The University of Electro-communications1,The University of Tokyo2
Gaurav Kapil1,2,Takeru Bessho2,Qing Shen1,Hiroshi Segawa2,Shuzi Hayase1
The University of Electro-communications1,The University of Tokyo2
Recently, tin-lead (Sn-Pb) perovskite solar cells (PSCs) are getting a good deal of attention because of their ideal bandgap that lies in the high efficiency zone of Shockley-Queisser (SQ) limit plot for the single-junction solar cells [1]. To date, efficient Sn-Pb PSCs are fabricated on the conventional hole transport layer, PEDOT: PSS, which is acidic and hygroscopic and hence not an ideal candidate for the long-term stability of these solar cells [2,3]. Our group has reported previosuly a power conversion efficiency (PCE) of 21.74% in Sn-Pb PSCs using Cs<sub>0.025</sub>FA<sub>0.475</sub>MA<sub>0.5</sub>Sn<sub>0.5</sub>Pb<sub>0.5</sub>I<sub>3</sub>Br<sub>3-x</sub> (1.25 eV) absorber layers, which is among the best reported values so far using the narrow bandgap Sn-Pb perovskites. To further enhance the PCE, in this work, we have realized that replacement of PEDOT: PSS is necessary to increase the PCE and stability of these solar cells. Therefore, we replaced PEDOT: PSS completely with hole selective monolayers (HSMs), which is the first report of using HSMs in Sn-Pb PSCs. The idea is partly inspired by the recent development in Pb-PSCs as well. Moreover, we have reported that the junction between transparent conducting oxide (TCO) electrode and HSM plays a very important role in reducing the open-circuit voltage (<i>Voc</i>) loss. Finally, we have achieved the highest PCE of 23.3% which is also among the highest reported PCEs in the field of PSCs using inverted p-i-n configuration. Our work further provides a deep insight into device engineering to improve solar cell efficiencies. Hence, we believe that the fabrication strategy reported is very important in improving the PCE of not only Sn-Pb PSCs but also for other PSCs employing inverted device architecture.<br/><b>References</b><br/>W. Shockley, H. J. Queisser, <i>J. Appl. Phys.</i> 1961, 32, 510.<br/>K. Xiao and H. Tan et al., <i>Nature Energy</i>, 2020, 5, 870-880.<br/>G. Kapil and S. Hayase et al., <i>Adv. Energy. Mat.</i>, 2021, DOI: 10.1002/aenm.202101069