Molecular Design of Hole Transport Materials to Immobilize Ion Motion for Photostable Perovskite Solar Cells

Poor operational stability is a crucial factor limiting the further application of perovskite solar cells (PSCs). Organic semiconductor layers can be a powerful means for reinforcing interfaces and inhibiting ion migration. Herein, two hole‐transporting molecules, pDPA‐SFX and mDPA‐SFX, are synthesized with tuned substituent connection sites. The meta‐substituted mDPA‐SFX results in a larger dipole moment, more ordered packing, and better charge mobility than pDPA‐SFX, accompany with strong interface bonding on perovskite surfaces and suppressed ion motion as well. Importantly, mDPA‐SFX‐based PSCs exhibit an efficiency that has significantly increased from 22.5% to 24.8% and a module‐based efficiency of 19.26% with an active area of 12.95 cm2. The corresponding cell retain 94.8% of its initial efficiency at maximum power point tracking (MPPT) after 1,000 h (T95 = 1,000 h). The MPPT T80 lifetime is as long as 2,238 h. This work illustrates that a small degree of structural variation in organic compounds leaves considerable room for developing new HTMs for light stable PSCs.