I am a new researcher in the field of perovskite. From a long time I am trying to achive an efficiency over 20 % but I am unable to get it due to limited Voc. I am working on FTO/TiO2 (spin coating)/FAPbI3 one step deposition/ PEAI passivation/ Spiro/ Au. The peroskite deposition is taken place inside a glove box with O2 and H2O level < 2 ppm. The antisolvent (cholorobenzene) dripping is last 10 sec of the 2nd spin coating speed, annealing at 120* C for 60 min or 150 * C for 20 min. My Voc is stuck between 0.9 to 1 V for TiO2 ETL. I tried changing the TiO2 with SnO2 and used 1:5 SnO2 to DI water solution at 4000 rpm 30 sec and annealing at 150*C for 1 hour. But in this case my Voc is varying between 0.8-0.9 V. The Jsc mostly varies between 22 - 24 mA/cm2, FF between 68-77 % and Efficiency between 15 -18 %. The perovskite films seems very nice with no defects.
I do not know which step I am not following properly to increase the device efficiency further. Please provide me your valuable suggestion to improve the device performance. It would be great help.
Your low V_OC in FAPbI₃ cells mainly comes from non-radiative recombination at the interfaces and trap states in the pure FA absorber. Using additives like MACl or small Cs incorporation, optimizing SnO₂ quality, and applying gentler surface passivation (e.g. MeO-PEAI with controlled thickness) can significantly suppress recombination. Together with better antisolvent engineering to fully remove DMSO, these adjustments typically raise V_OC and push efficiency.
Thank you so much, Mir Waqas Alam, for responding. I used MACl and a small amount of Cs in the perovskite film, but I still could not achieve a higher Voc.
Your Voc is mainly limited by interfacial recombination rather than bulk film quality. A few practical steps that usually help:
- ETL: Use high-quality colloidal SnO₂ (dilution 1:6–1:10), anneal at 150 °C for ~30 min, and add an ultra-thin interlayer (e.g. PEIE or KF/KCl) to passivate traps.
- Perovskite layer: Introduce small CsI or MACl additives to stabilize FAPbI₃ and promote larger grains. Try hot-casting (substrate 100–120 °C) and switch antisolvent to ethyl acetate or IPA instead of late chlorobenzene dripping.
- Passivation: Too much PEAI can reduce Voc. Use lower concentration/shorter time, or try alternatives such as MeO-PEAI or BACl.
- HTL: Optimize Spiro-OMeTAD (reduce tBP, use proper LiTFSI levels), or compare with PTAA + self-assembled monolayers (e.g. Me-4PACz).
- Diagnostics: Suns-Voc or steady-state PL can confirm if losses are at the ETL/perovskite interface. A very thin C60 or PCBM layer at this interface often improves Voc.
With FAPbI₃ you should target Voc ≈1.15–1.20 V, Jsc 23–25 mA/cm², and FF ≥78 %, which should take you above 20 % efficiency.
This article will be helpful.
"How to Make over 20% Efficient Perovskite Solar Cells in Regular (n–i–p) and Inverted (p–i–n) Architectures"
Thank you very much, Charafeddine Sedrati for responding. I will follow all the steps mentioned by you. Thank you again for the help.
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