Researchers from the School of Chemical Engineering at the Clean Energy Research Center, Jeonbuk National University, Republic of Korea, have reported findings on interface engineering for back-contact perovskite solar cells (BC-PSCs). BC-PSCs remove front-contact electrodes, enabling improved photon absorption and potentially higher charge collection. The study introduced an electron transport layer formed by combining nanoparticle SnO2 with a sol–gel SnO2 solution through a spin-coating process. This approach improved interfacial contact, reduced trap-assisted recombination, and aligned energy levels for more efficient carrier extraction. Using conductive atomic force microscopy and photocurrent mapping, the researchers observed improved charge transport behaviour in the device structure. The resulting BC-PSC achieved a maximum power conversion efficiency of 4.52 %. The back-contact architecture also allowed direct investigation of interfacial charge dynamics relevant to carrier transport mechanisms.