Selenium-Based Solar Cell with Conjugated Polymers as Both Electron and Hole Transport Layers to Realize High Water Tolerance as well as Good Long-Term and Thermal Stability

Solar cells with varied absorbers, ranging from crystalline silicon to perovskite materials, are very vulnerable to water. Expensive and complicated encapsulation is needed to protect the devices. Thus, it is highly desirable to achieve encapsulation-free solar cells with high water tolerance. Herein, encapsulation-free selenium (Se)-based solar cells (SSCs) with hydrophobic polymers as electron and hole transport layers are presented and can successfully tolerate the aqueous conditions. Moreover, it is found that the photocurrent–time curve under the aqueous/ambient environment can be smoothly fitted into the first-order exponential models. The photocurrent of water-soaking SSCs can recover to its original value after drying in the air, which proves the great water tolerance of fabricated SSCs. Furthermore, the SSCs also show good long-term and thermal stability. The viability of encapsulation-free SSCs under a harsh environment provides opportunities to further explore the interactions among light, water, and solar cells as well as make large-scale industrialization applications of SSCs much easier.