Solution‐processed Cu2O and CuO are used as hole transport materials in perovskite solar cells. The cells show significantly enhanced open circuit voltage V
oc, short‐circuit current J
sc, and power ...conversion efficiency (PCE) compared with PEDOT cells. A PCE of 13.35% and good stability are achieved for Cu2O cells, making Cu2O a promising material for further application in perovskite solar cells.
A family of perovskite light absorbers (NH4)3Sb2IxBr9−x (0≤x≤9) was prepared. These materials show good solubility in ethanol, a low‐cost, hypotoxic, and environmentally friendly solvent. The light ...absorption of (NH4)3Sb2IxBr9−x films can be tuned by adjusting I and Br content. The absorption onset for (NH4)3Sb2IxBr9−x films changes from 558 nm to 453 nm as x changes from 9 to 0. (NH4)3Sb2I9 single crystals were prepared, exhibiting a hole mobility of 4.8 cm2 V−1 s−1 and an electron mobility of 12.3 cm2 V−1 s−1. (NH4)3Sb2I9 solar cells gave an open‐circuit voltage of 1.03 V and a power conversion efficiency of 0.51 %.
Unleaded: Lead‐free perovskite materials (NH4)3Sb2IxBr9−x (0≤x≤9) were developed by using ethanol as the solvent. (NH4)3Sb2I9 single crystals were prepared and the crystal structure was analyzed. Solar cells were made by using (NH4)3Sb2IxBr9−x as the light absorbers. (NH4)3Sb2I9 solar cells gave a high open‐circuit voltage of 1.03 V and a power conversion efficiency of 0.51 %.
The work functions for charge transport layers in perovskite solar cells affect device performance significantly. In this work, the regular poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate ...(PEDOT:PSS) is modified by adding a polymer electrolyte PSS‐Na to improve its HTL function in perovskite solar cells. The modified PEDOT:PSS films (called m‐PEDOT:PSS) possess higher work function than the regular one. Its energy level matches the valence band of perovskite very well, leading to enhanced Voc and PCE (power conversion efficiency). When CH3NH3PbI3 is used as the light absorber, the cell with PEDOT:PSS HTL gives a Voc of 0.96 V and a PCE of 12.35%, while the cell with m‐PEDOT:PSS layer gives a Voc of 1.11 V and a PCE of 15.56%. Enhanced Voc and PCE are also achieved when CH3NH3PbI2Br or CH3NH3PbBr3 is used as the light absorber. The m‐PEDOT:PSS/CH3NH3PbBr3/PC61BM solar cells demonstrate an outstanding Voc of 1.52 V.
A modified poly(3,4‐ethylenedioxythiophene) (PEDOT) layer is developed and used as the HTL for perovskite solar cells, leading to enhanced performance. Using m‐PEDOT:PSS (1:2) as the HTL and CH3NH3PbI3 as the light absorber, a Voc of 1.11 V and a power conversion efficiency of 15.56% are achieved. A Voc of 1.52 V is obtained from CH3NH3PbBr3 solar cells, which is the highest Voc for perovskite/PCBM solar cells.
Drop‐casting was used to make MAPbI3 films for solar cells. The crystal growth in drop‐cast MAPbI3 films was regulated by adjusting temperature. A mechanism for the formation of different morphology ...was proposed by combining in situ crystal‐growth study with XRD measurements. The crystals in the films made at low temperature (60 °C) and high temperature (≥120 °C) are (110) and (200) oriented, respectively. The different crystal growth mode leads to quite different film morphology. Compared with spin‐coating, drop‐casting shows much better tolerance to humidity. MAPbI3 solar cells made under 88 % humidity delivered a PCE of 18.17 %, which is the highest PCE for perovskite solar cells made under >70 % humidity without antisolvent assistance.
MAPbI3 crystal growth in the films made by drop‐casting is regulated by changing the temperature. At low temperature (60 °C), the crystals are (110) oriented, needle‐like. At high temperature (>120 °C), the crystals are (200) oriented, presenting round grains. The different crystal growth mode leads to quite different film morphology and photovoltaic performance.
The rapid improvement in power conversion efficiencies (PCE) to record high levels have highlighted perovskite solar cells’ great potential to be commercialized in the near future. Continuous ...roll-to-roll (R2R) processing on flexible substrates enables ultra low-cost and high throughput manufacturing, which is essential for perovskite solar cells to make a breakthrough in cost per Watt compared to commercially established solar cells technologies. Here we demonstrate a facile spin-coating-free and R2R compatible blowing-assisted drop-casting (BADC) method to prepare CH3NH3PbI3 films for perovskite solar cells. The crystallinity and morphology of CH3NH3PbI3 films and device performance are significantly improved by optimization of the formulation with an NH4Cl additive. The perovskite solar cell prepared in air with a maximum PCE of 19.48% is obtained using modified poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (m-PEDOT:PSS) as the hole transport layer (HTL). The cells based on the structure of ITO/m-PEDOT:PSS/CH3NH3PbI3/PCBM/Ca/Al exhibit negligible current hysteresis. The optimized formulation is then successfully applied to slot-die coating on glass and subsequently to R2R on a flexible substrate, giving record PCEs of 15.57% and 11.16%, respectively.
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•A blowing-assisted drop-casting method was used to prepare CH3NH3PbI3 films in air. The morphology and crystallinity of CH3NH3PbI3 films were improved significantly by using NH4Cl additive.•Planar p-i-n perovskite solar cell with a PCE of 19.48% was achieved using modified PEDOT:PSS as the hole transport layer.•Cells with PCEs of 15.57% and 11.16% were obtained by using the slot-die coating and the R2R process, respectively.
An electrically modulated single‐/dual‐color imaging photodetector with fast response speed is developed based on a small molecule (COi8DFIC)/perovskite (CH3NH3PbBr3) hybrid film. Owing to the type‐I ...heterojunction, the device can facilely transform dual‐color images to single‐color images by applying a small bias voltage. The photodetector exhibits two distinct cut‐off wavelengths at ≈544 nm (visible region) and ≈920 nm (near‐infrared region), respectively, without any power supply. Its two peak responsivities are 0.16 A W−1 at ≈525 nm and 0.041 A W−1 at ≈860 nm with a fast response speed (≈102 ns). Under 0.6 V bias, the photodetector can operate in a single‐color mode with a peak responsivity of 0.09 A W−1 at ≈475 nm, showing a fast response speed (≈102 ns). A physical model based on band energy theory is developed to illustrate the origin of the tunable single‐/dual‐color photodetection. This work will stimulate new approaches for developing solution‐processed multifunctional photodetectors for imaging photodetection in complex circumstances.
A tunable dual‐color imaging photodetector with a fast response speed (≈102 ns) is developed by constructing a type‐I p–n heterojunction of CH3NH3PbBr3/COi8DFIC. Dual‐color imaging can be switched to single‐color imaging by applying a small bias voltage.
Heating‐assisted deposition is an industry‐friendly scalable deposition method. This manufacturing method is employed together with slot die coating to fabricate perovskite solar cells via a ...roll‐to‐roll process. The feasibility of the method is demonstrated after initial testing on a rigid substrate using a benchtop slot die coater in air. The fabricated solar cells exhibit power conversion efficiencies (PCEs) up to 14.7%. A nonelectroactive polymer additive is used with the perovskite formulation and found to improve its humidity tolerance significantly. These deposition parameters are also used in the roll‐to‐roll setup. The perovskite layer and other solution‐processed layers are slot die‐coated, and the fabricated device shows PCEs up to 11.7%, which is the highest efficiency obtained from a fully roll‐to‐roll processed perovskite solar cell to date.
Roll‐to‐roll processed perovskite solar cells are fabricated using slot‐die coating by the hot deposition method. The hot deposition approach is scalable and can be performed in an uncontrolled ambient environment without additional processes. A polymer additive, polyethylene oxide, is introduced to improve the processability and proves useful for improving tolerance to humidity, resulting in improved reliability for industrial manufacturing.
Highlights
The slot-die-coated porous PbI
2
:CsI film assisted with nitrogen blowing can promote the rapid and complete transformation of perovskite film.
The crystallinity and morphology of ...slot-die-coated perovskite film are significantly improved by controlling substrate temperature.
Fully slot-die-coated perovskite solar cells achieve a power conversion efficiency (PCE) of 18.13%, and fully roll-to-roll printed flexible PSCs achieve a PCE of 13.00% in ambient condition.
Perovskite solar cells (PSCs) have attracted tremendous attention as a promising alternative candidate for clean energy generation. Many attempts have been made with various deposition techniques to scale-up manufacturing. Slot-die coating is a robust and facile deposition technique that can be applied in large-area roll-to-roll (R2R) fabrication of thin film solar cells with the advantages of high material utilization, low cost and high throughput. Herein, we demonstrate the encouraging result of PSCs prepared by slot-die coating under ambient environment using a two-step sequential process whereby PbI
2
:CsI is slot-die coated first followed by a subsequent slot-die coating of organic cations containing solution. A porous PbI
2
:CsI film can promote the rapid and complete transformation into perovskite film. The crystallinity and morphology of perovskite films are significantly improved by optimizing nitrogen blowing and controlling substrate temperature. A power conversion efficiency (PCE) of 18.13% is achieved, which is promising for PSCs fabricated by two-step fully slot-die-coated devices. Furthermore, PSCs with a 1 cm
2
area yield a champion PCE of 15.10%. Moreover, a PCE of 13.00% is obtained on a flexible substrate by the roll-to-roll (R2R) coating, which is one of the highest reported cells with all layers except for metal electrode fabricated by R2R process under ambient condition.
The work functions for charge transport layers in perovskite solar cells affect device performance significantly. In this work, the regular poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate ...(PEDOT:PSS) is modified by adding a polymer electrolyte PSS‐Na to improve its HTL function in perovskite solar cells. The modified PEDOT:PSS films (called m‐PEDOT:PSS) possess higher work function than the regular one. Its energy level matches the valence band of perovskite very well, leading to enhanced
V
oc
and PCE (power conversion efficiency). When CH
3
NH
3
PbI
3
is used as the light absorber, the cell with PEDOT:PSS HTL gives a
V
oc
of 0.96 V and a PCE of 12.35%, while the cell with m‐PEDOT:PSS layer gives a
V
oc
of 1.11 V and a PCE of 15.56%. Enhanced
V
oc
and PCE are also achieved when CH
3
NH
3
PbI
2
Br or CH
3
NH
3
PbBr
3
is used as the light absorber. The m‐PEDOT:PSS/CH
3
NH
3
PbBr
3
/PC
61
BM solar cells demonstrate an outstanding
V
oc
of 1.52 V.
