Eliminating Charge Accumulation via Interfacial Dipole for Efficient and Stable Perovskite Solar Cells

Abstract

Elimination of interfacial charge trapping is still a challenge for promoting both efficiency and operational stability of organic–inorganic perovskite solar cells (PSCs). Herein, an effective interface dipole, trimethylamine oxide (TMAO) regarded as a connecting bridge, is inserted between the electron transport layer (ETL) and the perovskite layer to suppress charge accumulation and fabricate highly efficient and stable PSCs. As demonstrated by energy level alignment and morphology characterization, TMAO dipoles could achieve a decreased energetic barrier of electron transport and substantial padding of perovskite in the mesoporous ETL. Thus, they facilitate the charge transfer and reduce trapped charge densities as well as recombination centers at the interface between perovskite and ETL. These desirable properties improve the device efficiency to 21.77% and weaken the hysteresis index almost to 0. More importantly, the stability of the unencapsulated PSCs is remarkably enhanced. The findings provide valuable insights into the role of a dipolar molecule in boosting the performance of PSC devices.

Tuning halide perovskite energy levels

“…For instance, Zhang et al 16 functionalized ZnO with dipolar molecules for organic solar cells. Yang et al 17 inserted an interlayer between TiO 2 and perovskite, improving the charge extraction, similarly to Liu et al 18 , who instead modified the interface between SnO 2 and perovskite. A few cases can also be found related to WF tuning of the perovskite layer.…”

Efficient and Stable Perovskite‐Based Photocathode for Photoelectrochemical Hydrogen Production

“…[ 19 ] Also, the degradation of J ph in the OHP photocathodes can be accelerated under operation conditions by relatively sluggish charge transfer by hydrogen ion reduction as compared with solar cell systems. [ 48–51 ] To confirm the stability of our OHP photocathodes, chronoamperometry measurements were carried out for both Pt/EGaIn‐OHP:Pro and bare EGaIn‐OHP:Pro (Figure 4e and Figure S9c, Supporting Information). As shown in Figure 4e, the J ph of the Pt/EGaIn‐OHP:Pro photocathode is −21 mA·cm −2 at 0 h and −17.7 mA·cm −2 at 12 h. In particular, J ph is −12.1 mA·cm −2 at 54 h before the light was turned off.…”

Understanding the Synergistic Effect of Device Architecture Design toward Efficient Perovskite Light‐Emitting Diodes Using Interfacial Layer Engineering

“…Therefore, serious charge imbalance can be caused to reduce the efficiency and excess charges can easily accumulate at the interface between MHP and neighboring layers. [ 39–42 ] Accumulated charges in EML can degrade MHP. [ 39–42 ] Also, accumulated charges can easily migrate to the counterpart transport layer (holes to ETL, electrons to HTL), due to relatively deep highest occupied molecular orbital (HOMO) level of MHP compared to conventional organic emitters.…”

“…[ 39–42 ] Accumulated charges in EML can degrade MHP. [ 39–42 ] Also, accumulated charges can easily migrate to the counterpart transport layer (holes to ETL, electrons to HTL), due to relatively deep highest occupied molecular orbital (HOMO) level of MHP compared to conventional organic emitters. Leakage of major carrier reduces the efficiency and induce unwanted emission from the transport layer.…”