Browsing by Author "Bolink, Henk J."

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Citation - WoS: 33
Citation - Scopus: 34
Crystal Reorientation and Amorphization Induced by Stressing Efficient and Stable P-I Vacuum-Processed Mapbi(3) Perovskite Solar Cells
(Wiley, 2021) Kaya, İsmail C.; Zanoni, Kassio P. S.; Palazon, Francisco; Sessolo, Michele; Akyıldız, Hasan; Sönmezoğlu, Savaş; Bolink, Henk J.
Herein, the long-term stability of vacuum-deposited methylammonium lead iodide (MAPbI(3)) perovskite solar cells (PSCs) with power conversion efficiencies (PCEs) of around 19% is evaluated. A low-temperature atomic layer deposition (ALD) Al2O3 coating is developed and used to protect the MAPbI(3) layers and the solar cells from environmental agents. The ALD encapsulation enables the MAPbI(3) to be exposed to temperatures as high as 150 degrees C for several hours without change in color. It also improves the thermal stability of the solar cells, which maintain 80% of the initial PCEs after aging for approximate to 40 and 37days at 65 and 85 degrees C, respectively. However, room-temperature operation of the solar cells under 1sun illumination leads to a loss of 20% of their initial PCE in 230h. Due to the very thin ALD Al2O3 encapsulation, X-ray diffraction can be performed on the MAPbI(3) films and completed solar cells before and after the different stress conditions. Surprisingly, it is found that the main effect of light soaking and thermal stress is a crystal reorientation with respect to the substrate from (002) to (202) of the perovskite layer, and that this reorientation is accelerated under illumination.
Citation - WoS: 66
Citation - Scopus: 68
Efficient Vacuum-Deposited Perovskite Solar Cells With Stable Cubic Fa(1)(-X)ma(x)pbi(3)
(AMER CHEMICAL SOC, 2020) Gil-Escrig, Lidon; Dreessen, Chris; Kaya, İsmail Cihan; Kim, Beom-Soo; Palazon, Francisco; Sessolo, Michele; Bolink, Henk J.
Preparation of black formamidinium lead iodide (FAPbI(3)) requires high-temperature annealing and the incorporation of smaller A-site cations, such as methylammonium (MA(+)), cesium, or rubidium. A major advantage of vacuum processing is the possibility to deposit perovskite films at room temperature (RT), without any annealing step. Here we demonstrate stabilization of the cubic perovskite phase at RT, in a three-source co-sublimation method. We found that the MA(+) incorporation is a self-limiting process, where the amount of MA(+) which is incorporated in the perovskite is essentially unvaried with increasing MAI deposition rate. In this way a phase-pure, cubic perovskite with a bandgap of 1.53 eV can be obtained at room temperature. When used in fully vacuum-processed perovskite solar cells, PCEs up to 18.8% are obtained. Despite the presence of MA(+), the solar cells were found to be thermally stable and maintained 90% of their initial efficiency after 1 month of continuous operation.
Citation - WoS: 14
Citation - Scopus: 14
Intrinsic Organic Semiconductors as Hole Transport Layers in P-I Perovskite Solar Cells
(Wiley-V C H Verlag Gmbh, 2022) Susic, Isidora; Zanoni, Kassio P. S.; Paliwal, Abhyuday; Kaya, İsmail C.; Hawash, Zafer; Sessolo, Michele; Bolink, Henk J.
Thin polymeric and small-molecular-weight organic semiconductors are widely employed as hole transport layers (HTLs) in perovskite solar cells. To ensure ohmic contact with the electrodes, the use of doping or additional high work function (WF) interlayer is common. In some cases, however, intrinsic organic semiconductors can be used without any additive or buffer layers, although their thickness must be tuned to ensure selective and ohmic hole transport. Herein, the characteristics of thin HTLs in vacuum-deposited perovskite solar cells are studied, and it is found that only very thin (<5 nm) HTLs readily result in high-performing devices, as the HTL acts as a WF enhancer while still ensuring selective hole transfer, as suggested by ultraviolet photoemission spectroscopy and Kelvin probe measurements. For thicker films (>= 5 nm), a dynamic behavior for consecutive electrical measurements is observed, a phenomenon which is also common to other widely used HTLs. Finally, it is found that despite their glass transition temperature, small-molecule HTLs lead to thermally unstable solar cells, as opposed to polymeric materials. The origin of the degradation is still not clear, but might be related to chemical reactions/diffusion at the HTL/perovskite interface, in detriment of the device stability.